Semiconductor light-emitting device, method for manufacturing the same, and light-emitting apparatus including the same

ABSTRACT

A nitride semiconductor light-emitting device includes a layered portion emitting light on a substrate. The layered portion includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. The periphery of the layered portion is inclined, and the surface of the n-type semiconductor layer is exposed at the periphery. An n electrode is disposed on the exposed surface of the n-type semiconductor layer. This device structure can enhance the emission efficiency and the light extraction efficiency.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 10/522,887 filed on Dec. 22, 2005 now U.S. Pat. No.7,511,311, which was the National Stage of International Application No.PCT/JP2003/09836, filed on Aug. 1, 2003. The disclosures of U.S. patentapplication Ser. No. 10/522,887 and International Application No.PCT/JP2003/09836 are hereby incorporated by reference.

This application is based on Japanese Patent Application Nos.2002-225043 filed on Aug. 1, 2002 and 2002-256884 filed on Sep. 2, 2002,the contents of which are incorporated hereinto by reference.

TECHNICAL FIELD

The present invention relates to semiconductor light-emitting devices,and particularly to a light-emitting device including a nitridesemiconductor containing nitrogen, and to a method for manufacturing thesame. Specifically, the nitride semiconductor light emitting deviceincludes GaN, AlN, InN, and their mixed crystals, group III-V nitridesemiconductors (In_(b)Al_(c)Ga_(1-b-c)N, 0≦b, 0≦d, b+d<1), and is usedin light-emitting apparatuses, projectors, cluster lamps, illuminations,optical coupling devices, optical detectors, optical communicationdevices, light sources of optical fiber modules, and so forth.

BACKGROUND ART

Light-emitting diodes including gallium nitride compound semiconductorsare increasingly used particularly for relatively short wavelengthregions, such as ultraviolet region and the blue region, in recentyears. Since the gallium nitride semiconductor is of direct transitionand has a high luminous efficiency, the range of its applications isexpanding, accordingly.

For such light-emitting devices, various structures have been proposed,particularly in the shape of the semiconductor composite and thestructure and arrangement of electrodes.

DISCLOSURE OF INVENTION First Aspect

The object of the present invention is to provide a high-power, reliablelight-emitting device including a semiconductor composite or layeredportion having a shape ensuring high luminous efficiency and,particularly, superior light extraction efficiency and heat radiationcharacteristics. For example, the light-emitting device includes astructured composite, or layered structure, including a luminescentlayer disposed between a first conductivity type layer and a secondconductivity type layer. The structured composite includes a structuredportion including the luminescent layer, and has an inclined peripheryat a junction (p-n junction) of the first and second conductivity typelayers, the surface of the substrate, and an electrode-forming surface.The lower surface of the inclined structured portion is formed in asquare or polygonal shape. The inclined periphery includes inclined sidesurfaces so that the corners of the lower surface of the structuredportion are curved or cut off in such a manner that the width of theside surfaces gradually increase upward from the lower surface. In alight-emitting device having a luminescent portion close to the uppersurface rather than the lower surface, this structure helps the lightemitted from the luminescent portion to reflect and diffuse at theinclined side surfaces in the corners close to the luminescent portion,thus efficiently extracting the light outward.

Specifically, the light-emitting device has the following structure.

The semiconductor light-emitting device 10000 has a structure includinga luminescent layer 4 disposed between a first conductivity type layer 2and a second conductivity type layer 3. At least part of the structuredefines a structured portion 10 which has a lower surface 10 g with awidth and an upper surface 10 f with a smaller width than that of thelower surface 10 f in sectional view, and inclined opposing sidesurfaces: first side surfaces 10 x; and second side surfaces 10 y. Thewidth of the first side surfaces 10 x increases from the lower surface10 g side toward the upper surface 10 f; the width of the second sidesurfaces 10 y increases from the upper surface 10 f side toward thelower surface 10 g. More specifically, the structured portion 10 of thedevice has the lower surface 10 a and the upper surface 10 f with asmaller area than that of the lower surface 10 g, and the side surfaces10 x between the dotted chain lines 10 x-1 and 10 x-2 define the corners10 g-x and 10 f-x of the structured portion 10 of the device and have awidth increasing toward the upper surface 10 f from the lower surface 10g, as shown in FIGS. 53A and 53C. On the other hand, the side surfaces10 y are formed so as to have a width decreasing toward the uppersurface. Thus, the widths of the side surfaces 10 x and 10 y are variedin reverse to each other in the height direction (toward the uppersurface) of the structured portion, that is, the width of the sidesurfaces 10 x is increased; the width of the side surfaces 10 y isreduced. Accordingly, the proportion of lengths of the sides defining aplane at a certain height (a plane parallel to the upper surface of thestructured portion or a plane having a normal in the height direction)varies, and the proportion of occupancies of the side surfaces above theplane also varies. Consequently, reflection of light emitted from thelight-emitting device, designated by the arrows in FIG. 53B, from theside surfaces to the lower surface is diffused, as shown in FIG. 53B.Thus, the light-emitting device exhibits superior uniformity and lightextraction though, in light-emitting devices, light is generally liableto be concentrated.

In the semiconductor light-emitting device, the first side surfaces 10 xare formed in the corners defined by the sides 10 g-1 and 10 g-2 of thelower surface 10 g. For example, as shown in FIG. 53A showing astructured portion 10, FIG. 53B being a fragmentally enlarged view ofFIG. 53A, and FIG. 53C showing another form of the structured portion10, the structured portion 10 is defined by a lower surface 10 g in asquare or polygonal shape, an upper surface, and an inclined peripherysuch that the width in sectional view of the structured portion 10decreases toward the upper surface from the lower surface 10 g, and thefirst side surfaces 10 x are each formed such that the corners of thelower surface or upper surface are curved or cut off. The side surfaces10 x can reflect light propagated in the light-emitting deviceeffectively toward the lower surface, or allow the light to be extractedfrom the upper surface side.

In the semiconductor light-emitting device, the luminescent layer isdisposed inside the structured portion. As designated by the dottedlines 4 in FIGS. 53A to 53D, the luminescent layer functioning as thelight source of the light-emitting device is provided between the uppersurface and the lower surface of the structured portion having theabove-described shape. Consequently, light can be reflected at the sidesurfaces and extracted at a short distance from the light source,reducing undesirable propagation inside the device. Thus, thelight-emitting device can exhibit high light-extraction efficiency.

In the semiconductor light-emitting device, the lower surface may have asquare or polygonal shape, the second side surfaces are formed on thesides of the lower surface, and the first side surfaces are formed inthe corners of the lower surface. The corners 10 x or first sidesurfaces 10 x are formed in divergent shapes whose width increasestoward the upper surface, while the second side surfaces 10 y are formedin another divergent shape whose width increases toward the lowersurface and the bases of the second surfaces 10 y define the sides 10g-1 and 10 g-2 of the lower surface. Thus, the lower surface can beformed in a desired shape, and the shape of the corners can be divergedupward. Thus, the light-emitting device of the present invention can beachieved in various shapes.

The structured portion of the semiconductor light-emitting device may beof frustum. By forming the structured portion in frustum, as in thebelow-described second and third aspects, the degree of in-planeintegration is increased, and the resulting light-emitting device canexhibit a high processing precision, advantageously.

In the semiconductor light-emitting device, the first side surfaces maybe curved to be convex outward. As shown in FIG. 53B, by curving thefirst side surfaces and the second side surfaces at different curvatureradiuses, or by curving the first side surfaces and forming the secondside surfaces flat, light can be diffused in various directions to bereflected or extracted. Thus, the concentration of light is reduced.

In the semiconductor light-emitting device, the first side surfaces maydefine rounded sides of the lower surface and the upper surface, and thecurvature radius of the rounded sides of the upper surface may be largerthan that of the lower surface. For example, as shown in FIG. 53B, byincreasing the curvature radius upward, light propagationcharacteristics in the direction of the normal of the upper surface varyfrom those of the inclined surface (region where the inclined surface isprojected in the direction of the normal), and light propagation in thein-plane direction can be promoted. In addition, the curved surfacewhose curvature radius increasing toward the upper surface, as shown inFIG. 53B, leads to a high precision in forming a mask. Accordingly, theprecision in forming electrodes and a protective layer on the inclinedsurfaces can be increased. Thus, a precise device structure can beprovided and the resulting device can exhibit superior characteristics.

The light-emitting device may have a plurality of the structuredportion, and an electrode structure is provided so that the structuredportions substantially simultaneously emit light.

The light-emitting device may have a pair of a positive electrode and anegative electrode on the same surface side over the upper surface ofthe structured portion. This structure can lead to the same structure asin a second aspect described later.

In the light-emitting device, one of the pair of the electrodes maycover part of the periphery of the structured portion.

In the light-emitting device, the structured portions may be disposedseparately on a substrate, and electrodes are provided so that thestructured portions substantially simultaneously emit light.

The upper surface of the structured portion defines a mounting surfacewhich opposes a mounting base when the light-emitting device is disposedon the mounting base. One of the pair of the electrodes is disposed onthe surface of a substrate, and the other comprises a wiring structuredisposed on the mounting base side so as to be connected to the uppersurfaces of the separately disposed plurality of the structuredportions. Specifically, as shown in FIG. 16B, one of the electrodes isdisposed on the semiconductor multilayer board side; the other, on themounting surface side. Thus, this structure makes efficient use ofspace. For example, various devices, such as a reflection film, alight-extraction film, and a light-transforming member, can be disposedin the spaces between the structured portions. In addition, if thepositive and negative electrodes are disposed in a solid intersectionseparated by an insulating layer, on the board side, leakage resultingfrom the solid intersection can be overcome.

The light-emitting device according may have a pair of electrodesdisposed separately on the upper surface side of the structured portionand on the lower surface side. The pair of the electrodes arerespectively disposed on the surface of the first conductivity typelayer and the surface of the second conductivity type layer. Thisstructure can be applied to a light-emitting device in which electrodesoppose each other, according to a third aspect described later.

The light-emitting device may further include a light-transmissiveinsulating layer covering the periphery of the structured portion, and afilling member around the periphery with the light-transmissiveinsulating layer therebetween. When the periphery of the structuredportion acts as a reflector from which light reflect inward, asdescribed above, light leaked outward can be reflected at thelight-transmissive layer covering the periphery and the surface at thestructured portion side of, for example, a metal reflection film. Thus,light-emitting device has several reflection structures in the outerregion to enhance the light control and emission efficiency.

The light-emitting device may have a plurality of the structuredportion, and the structured portions are separated from one another by aprotruding filling member. As in the third aspect described later, thefilling member, a metal member 7 may be used as the filling member.Thus, the resulting device can exhibit superior heat radiation, lightreflection, and mechanical strength.

The luminescent layer may be disposed inside the structured portion, andthe filling member protrudes below the luminescent layer toward thelower surface side of the structured portion. Thus, the filling memberis positioned close to the light-emitting device being a heat and lightsource to provide an improved structure.

Second Aspect

Gallium nitride compound semiconductors are generally deposited on aninsulating sapphire substrate, and this causes the following problems:First, both the n electrode and the p electrode must be formed above agallium nitride semiconductor on the sapphire substrate, andparticularly the n electrode is disposed in the non-luminescent region.The n electrode repeatedly reflects and absorbs light generated from theluminescent region while the light is propagating in the GaN layer inthe lateral direction. Thus, the extraction efficiency is undesirablyreduced. Second, although emitted light is generally extracted in thedirection perpendicular to the surface of the substrate, relatively highproportion of light is emitted through the periphery of thelight-emitting diode. Consequently, emitted light cannot be efficientlyused, disadvantageously.

Accordingly, an object in the second aspect of the present invention isto provide a nitride semiconductor light-emitting device which preventsrepetitive reflection under the n electrode to reduce the absorption bythe n electrode, and thus exhibits a high extraction efficiency. Anotherobject is to provide a nitride semiconductor light-emitting device inwhich emitted light is efficiently used.

In view of the above-describe problems, the second aspect of the presentinvention is directed to a nitride semiconductor light-emitting deviceincluding: a substrate; a layered portion emitting light disposed on thesubstrate; and an n electrode. The layered portion includes an n-typesemiconductor layer, an active layer, and a p-type semiconductor layer,and has an inclined periphery at which the surface of the n-typesemiconductor layer is exposed. The n electrode is disposed on thesurface of the n-type semiconductor layer. The nitride semiconductorlight-emitting device having such a structure can increase the lightextraction efficiency.

Preferably, the n electrode is formed so as to surround the layeredportion. Thus, current is efficiently injected into the structuredcomposite of the device even if the surface in contact with theelectrode (surface for current injection into the semiconductorcomposite) has a small area.

In the nitride semiconductor light-emitting device, the n electrode maycontinuously extend to the lower surface of the substrate through theside surfaces of the substrate. When light is emitted through alight-transmissive p ohmic electrode, the above-described structureallows light reflected from the side surfaces and the lower surface ofthe substrate to be emitted through the light-transmissive electrode.Thus, the light extraction efficiency can be increased.

The nitride semiconductor light-emitting device may have a plurality ofthe layered portion emitting light. Thus, a large-area nitridesemiconductor light-emitting device having a high emission efficiencycan be provided.

In the nitride semiconductor light-emitting device having the pluralityof layered portions, the respective n-electrodes for the layeredportions may be connected to each other to define a common electrode.Thus, the layered portions being luminescent regions can be readilyconnected in parallel.

In the nitride semiconductor light-emitting device having the pluralityof layered portions, the layered portions may have respective p ohmicelectrodes in ohmic contact with the respective p-type semiconductorlayers, and the p ohmic electrodes are connected to each other, inaddition to connecting the respective n-electrodes to each other todefine a common electrode. Thus, the resulting nitride semiconductorlight-emitting device has the layered portions being the luminescentregions connected in parallel. Both positive and negative wiringelectrodes electrically connecting the layered portions may be providedon the substrate side. Alternatively, one (n-type layer being the firstconductivity type layer lying on the substrate side) of the electrodesmay be disposed on the substrate side, for example, on the surface ofthe substrate or on the exposed surface (electrode-forming surface) ofthe first conductivity type layer exposed at the layered portion, andthe other electrode (p-type layer being the second conductivity typelayer lying more distant from the substrate than the first conductivitytype layer) may be disposed on the mounting side, that is, the sideopposing a mounting base on which the device is mounted, such as a heatsink or a submount, or opposing a device-mounting portion or a mountinglead of a light-emitting apparatus so that the electrodes disposed abovethe plurality of layered portions are connected to each other. Also, theelectrode may be disposed on the mounting base (mounting device) side ormounting portion of the light-emitting apparatus, outside thelight-emitting device. This arrangement allows the plurality of layeredportions to be precisely connected to each other even if the protrudinglayered portions have rough upper surfaces and are difficult to wireprecisely. Also, other structures, such as a reflection layer,insulating layer, or a protective layer can easily be formed, and thusan appropriate device structure can be provided.

If light is emitted through the substrate in the nitride semiconductorlight-emitting device, it is preferable that the layered portion iscovered with a reflection layer to increase the light-extractionefficiency. In this instance, the substrate is preferably transparent.The transparent substrate is advantageous because of high transmissionof light and electromagnetic waves emitted from the light-emittingdevice, and less self-reduction.

In the nitride semiconductor light-emitting device, the metal layerserves as a connecting electrode for connecting the p ohmic electrodesof the p-type semiconductor layers of the layered portions.

In the nitride semiconductor light-emitting device, the reflection layermay be of a metal layer covering the layered portion with an insulatinglayer therebetween, or of a dielectric multilayer film. Alternatively,by appropriately adjusting the refractive index of the semiconductormaterials of the light-emitting layered portion, a light andelectromagnetic wave-transmissive insulating film whose refractive indexis also adjusted may be used as the reflection layer. This layer may beof a multilayer film. For example, a dielectric multilayer film made ofa distributed Bragg reflector (DBR), a light-reflection film, and aninsulating film may be used in combination.

In the nitride semiconductor light-emitting device, the inclinedperiphery may have a convex surface protuberating outward. By giving theperiphery a convex surface, a curved convex surface, protrudingsurfaces, a curved surface, or polyhedral surfaces, and by combining theperiphery structure with the convex corners of the structured portion inthe first aspect, light reflection control, increase of thelight-extraction efficiency, and control of the light density(particularly in the luminescent portion) can be achieved moreeffectively.

According to the second aspect of the present invention, the nitridesemiconductor light-emitting device has the inclined periphery, and then electrode is disposed on the surface of the n-type nitridesemiconductor layer exposed at the periphery, so that light absorptionby the n electrode can be prevented to increase the light-extractionefficiency. In particular, since the substrate and the layered portionhave different refractive indexes, and the electrode of the firstconductivity type layer (n electrode) is disposed on the inclinedperiphery of the layered portion, light in the light-emitting layeredportion can be propagated to the optically connected by the periphery.In since the electrode extends from the periphery of the layered portionto the substrate, the area of the electrode in contact with the devicecan be reduced.

Third Aspect

Japanese Unexamined Patent Application Publication No. 2001-313422 (page6, right column, line 8 to page 7, left column, line 42, FIGS. 8 and 9)has disclosed a method is liable to result in a short circuit betweenthe p layer and the n layer at the cross-section between the devices(side surfaces of the device after cutting), disadvantageously.Accordingly, a second object (first and second light-emitting devices)of the present invention is to provide a nitride semiconductorlight-emitting device having a structure capable of preventing a shortcircuit at the side surfaces, and a method for manufacturing the same.Japanese Unexamined Patent Application Publication No. 8-330629 (FIGS. 1to 3) has been known.

In view of this object (second object), a first nitride semiconductorlight-emitting device is provided according to the third aspect of thepresent invention. The nitride semiconductor light-emitting deviceincludes: an n-type nitride semiconductor layer; p-type nitridesemiconductor layer; and a luminescent layer formed of a nitridesemiconductor between the n-type nitride semiconductor layer and thep-type nitride semiconductor layer. At least the p-type nitridesemiconductor layer and the luminescent layer define a frustum layeredcomposite, and the layered composite is embedded in a metal member sothat the periphery of the layered composite is isolated. By use of themetal member being a filling member, the strength of the epitaxial layer(growth layer) can be enhanced in a device having a plurality ofprotruding layered composites on a wafer. Also, by embedding the fillingportion between the protruding layered composites (luminescentstructured portions) or recesses formed around the layered composites,the filling member can be disposed relatively close to the operationalportion (luminescent portion) of the device to contribute to radiationof heat generated from the operational portions (composites). Thus, heatradiation of the device can be enhanced, and the light-emitting devicecan exhibit high power and large-current operation. By disposing thefilling member in the vicinity of the luminescent portion, it canfunction as a reflection film or reflector, or the base of the resultingstructure.

A second nitride semiconductor light-emitting device according to thethird aspect of the present invention includes: an n-type nitridesemiconductor layer; p-type nitride semiconductor layer; and aluminescent layer formed of a nitride semiconductor between the n-typenitride semiconductor layer and the p-type nitride semiconductor layer,wherein at least the p-type nitride semiconductor layer and theluminescent layer define a frustum layered composite, and the layeredcomposite is supported by a metal member opposing the surface of thelayered composite.

In the nitride semiconductor light-emitting device having such astructure, the layered composite is embedded in the metal member so thatthe periphery of the layered composite is isolated, and the peripherydoes not damaged during or after cutting. The reliability is thereforeincreased.

The nitride semiconductor light-emitting device according to the presentaspect can have electrodes on both sides. Thus, the luminescent regioncan be increased in comparison with the nitride semiconductorlight-emitting device having positive and negative electrodes on oneside.

In the first and the second nitride semiconductor light-emitting device,preferably, the surface of the metal member opposite to the surfaceopposing to the layered composite is flat.

Thus, the device can be readily mounted on a mounting base in such amanner that the flat surface opposes the mounting base.

The first and the second nitride semiconductor light-emitting device mayfurther include a transparent electrode on one of two opposing surfacesof the n-type nitride semiconductor layer, and the other surface has thelayered composite, so that light is emitted through the transparentelectrode. The transparent electrode transmits light and electromagneticwaves in the device and diffuse injected current in a plane of thedevice, thus functioning as a transmissive current-diffusing conductor.The transparent electrode may comprise a transparent conductive film ora metal film having an opening or window for transmitting light andelectromagnetic waves, and is formed, for example, in a grid, branch, orradial manner.

This structure allows uniform current injection to the entireluminescent layer, and thus light can be uniformly emitted. Preferably,the transparent electrode is made of ITO because ITO is highlylight-transmissive and can reduce the resistance. In addition, an oxideconductive film, an oxide semiconductor, and a transparent conductivefilm may be used as the transparent electrode.

Preferably, the first and the second nitride semiconductorlight-emitting device further includes a p electrode containing Rh, andthe p electrode is disposed between the layered composite and the metalmember to establish an ohmic contact with the p-type nitridesemiconductor layer. Thus, peel of the electrode can be prevented. The pelectrode may be formed of materials suitable as the electrode, such asnoble metals and elements of the platinum group, and Rh is the mostsuitable from the viewpoint of reflectivity and adhesion.

In the first and the second nitride semiconductor light-emitting device,the layered composite may include a part or the entirety of the n-typenitride semiconductor layer.

In the first and the second nitride semiconductor light-emitting device,preferably, the metal member has a thickness of 50 μm or more from theviewpoint of maintaining the shape of the luminescent region withreliability.

The first and the second nitride semiconductor light-emitting device mayhave a plurality of the layered composite. Thus, a large-arealight-emitting device can be provided.

In the light-emitting device having the plurality of layered composites,the n-type nitride semiconductor layer may be common to the plurality ofthe layered composites and the plurality of the layered composites aredisposed on the common n-type nitride semiconductor layer.

According to the third aspect of the present invention, the nitridesemiconductor light-emitting device, which includes an n-type nitridesemiconductor layer, p-type nitride semiconductor layer, and aluminescent layer formed of a nitride semiconductor between the n-typenitride semiconductor layer and the p-type nitride semiconductor layer,has a frustum layered composite including at least the p-type nitridesemiconductor layer and the luminescent layer, and the layered compositeis embedded in a metal member so that the periphery of the layeredportion is isolated. Therefore, the periphery of the layered compositecan be prevented from being damaged during and after cutting. Thus, thereliability of the nitride semiconductor light-emitting device of thepresent invention can be increased.

Fourth Aspect

According to a fourth aspect of the present invention, a light-emittingapparatus is provided which includes the light-emitting device accordingto any one of the first to third aspects. The structure of the apparatusis as follows:

The light-emitting apparatus includes the light-emitting device and amounting portion on which the light-emitting device is placed. The lightemitting device is mounted on a support and then placed on the mountingportion.

In another form, the light-emitting apparatus includes thelight-emitting device and a light-transforming member for transformingpart of light emitted from the light-emitting device into light having adifferent wavelength.

Preferably, the light-transforming member comprises an aluminum garnetphosphor containing Al; at least one element selected from the groupconsisting of Y, Lu, Sc, La, Gd, Tb, Eu, and Sm; one of Ga and In, andat least one element selected from the rare earth elements.

Preferably, the light-transforming member comprises a phosphor expressedby (Re_(1-x)R_(x))₃(Al_(1-y)Ga_(y))₅O₁₂ (0<x<1 and 0≦y≦1, wherein Rerepresents at least one element selected from the group consisting of Y,Gd, La, Lu, Tb, and Sm; and R represents Ce or Ce and Pr).

Alternatively, the light-transforming member may comprise a nitridephosphor containing N; at least one element selected from the groupconsisting of Be, Mg, Ca, Sr, Ba, and Zn; and at least one elementselected from the group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf, andis activated by at least one element selected from the rear earthelements.

The nitride phosphor may be expressed by the general formulaL_(X)Si_(Y)N_((2/3X+4/3Y)):Eu or L_(x)Si_(Y)O_(z)N_((2/3X+4/3Y−2/3Z)):Eu(L represents Sr, Ca, or Sr and Ca).

The features according to the first aspect include those of the secondand the third aspect, and can be applied to them. For example, thesecond aspect leads to an embodiment according to the first aspect whichhas a pair of a positive electrode and a negative electrode, forexample, the electrode (p electrode) of the first conductivity typelayer (p-type layer) and the electrode (n electrode) of the secondconductivity type layer (n-type layer), on the same side of thesubstrate. The third aspect leads to an embodiment according to thefirst aspect in which a pair of a positive electrode and a negativeelectrode, for example, the electrode (p electrode) of the firstconductivity type layer (p-type layer) and the electrode (n electrode)of the second conductivity type layer (n-type layer), oppose each otherwith the structured composite of the light-emitting device therebetween.In the second and the third aspect, light-emitting devices using nitridesemiconductors will be described as the light-emitting device accordingto the first aspect. However, the invention (according to the first, thesecond, and the third aspect) is not limited to the nitridesemiconductor device. In the second and the third aspect, the firstconductivity type layer is the n-type nitride semiconductor layer; thesecond conductivity type layer is the p-type nitride semiconductorlayer. However, the conductivity type layers may be reversed. The samegoes for the electrodes disposed for the respective conductivity typelayers (the first and the second conductivity type player). The last twodigits of the reference numerals shown in the drawings and thespecification represent components used in the invention, embodiments,examples, and the corresponding figures, and the components having thesame numeral in the last two digits correspond to each other. Fornumerals whose last two digits are “00”, the last three or four digitsrepresent the same as in the above-described last two digits. The seconddigit from the right may represent a modification having the similarstructure. For example, for the layered structure 10 of thelight-emitting device, tens in the layered structure represent specificlayers; twenties, the electrode (n electrode) of the first conductivitytype layer (n-type layer); thirties, the electrode (p electrode) of thesecond conductivity type layer (p-type layer); and sixties, theconnecting electrode (wiring electrode). The figures are each aschematic illustration, and may partially be exaggerated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a light-emitting device according to Embodiment1 of the present invention.

FIG. 2 is a sectional view taken along line A-A′ in FIG. 1.

FIG. 3 is a plan view of a light-emitting device of a modificationaccording to Embodiment 1 of the present invention.

FIG. 4 is a sectional view taken along line B-B′ in FIG. 3.

FIG. 5 is a plan view of a light-emitting device according to Embodiment2 of the present invention.

FIG. 6 is a plan view of a light-emitting device according to Embodiment3 of the present invention.

FIG. 7 is a sectional view taken along line C-C′ in FIG. 6.

FIG. 8 is a sectional view of a light-emitting device according to amodification of Embodiment 3.

FIG. 9 is a plan view of a light-emitting device according to Embodiment4 of the present invention.

FIG. 10 is a plan view of a light-emitting device according to amodification of Embodiment 4.

FIG. 11 is a plan view of a light-emitting device according toEmbodiment 5 of the present invention, omitting a p electrode.

FIG. 12 is a plan view (including the p electrode) of the light-emittingdevice according to Embodiment 5 of the present invention.

FIG. 13 is a sectional view taken along line D-D′ in FIG. 12.

FIG. 14 is a plan view of a light-emitting device according to a firstmodification of Embodiment 5.

FIG. 15 is a plan view of a light-emitting device according to a secondmodification of Embodiment 5.

FIG. 16A is a plan view of a light-emitting device according to a thirdembodiment of Embodiment 5; and FIG. 16B is a sectional view of thelight-emitting device mounted on a mounting base, taken along line G-G′in FIG. 16A.

FIG. 17 is a plan view of a light-emitting device according toEmbodiment 6 of the present invention.

FIG. 18 is an fragmentary enlarged plan view of FIG. 17.

FIG. 19A is a sectional view taken along line E-E′ in FIG. 18; FIG. 19Bis a sectional view taken along line F-F′ in FIG. 18.

FIGS. 20A to 20C show a process for forming a layered portion having aninclined periphery of a nitride semiconductor light-emitting deviceaccording to the present invention.

FIG. 21 is a sectional view of a known light-emitting device.

FIG. 22 is a schematic representation of a preferred inclination angleof the inclined periphery of a nitride semiconductor light-emittingdevice according to the present invention.

FIGS. 23A to 23C show that layered portions and their arrangement in anitride semiconductor light-emitting device according to the presentinvention prevent a (p) electrode 731 from absorbing light.

FIG. 24 is a plan view of a light-emitting device according to a fourthmodification of Embodiment 5.

FIG. 25 is a plan view of a light-emitting device used in themeasurement of light-extraction efficiency in Embodiment 6 of thepresent invention.

FIG. 26 is a plan view of a light-emitting device used in themeasurement of light-extraction efficiency in Comparative Example (1) ofEmbodiment 6 of the present invention.

FIG. 27 is a plan view of a light-emitting device used in themeasurement of light-extraction efficiency in Comparative Example (2) ofEmbodiment 6 of the present invention.

FIG. 28 is a plan view of a light-emitting device used as a reference inthe measurement of light-extraction efficiency in Embodiment 6 of thepresent invention.

FIGS. 29A and 29B are a plan view of a light-emitting device used as areference in the comparative examples of Embodiment 6 of the presentinvention.

FIG. 30 is a schematic illustration showing the method for measuring theextraction efficiency in Embodiment 6 of the present invention.

FIG. 31 is a plan view of a light-emitting device according toEmbodiment 7 of the present invention.

FIG. 32 is a fragmentary enlarged plan view of the light-emitting deviceaccording to Embodiment 7.

FIG. 33A is a plan view (transparent view of the device structure) of alight-emitting device mounted on a mounting base according to Embodiment8 of the present invention; and FIG. 33B is a side view of FIG. 33Aviewed from the H direction.

FIG. 34 is a sectional view of a nitride semiconductor light-emittingdevice according to Embodiment 9 of the present invention.

FIG. 35 is a sectional view of a step after forming a semiconductorlayers on a sapphire substrate in a method for manufacturing a nitridesemiconductor light-emitting device according to Embodiment 9 of thepresent invention.

FIG. 36 is a sectional view of a step after etching the semiconductorlayers on a sapphire substrate in the method according to Embodiment 9.

FIG. 37 is a sectional view of a step after forming (p) electrodes onlayered composites in the method according to Embodiment 9.

FIG. 38 is a sectional view of a step after forming an insulating layer5 in the method according to Embodiment 9.

FIG. 39 is a sectional view of a step after forming a reflection layer 6in the method according to Embodiment 9.

FIG. 40 is a sectional view of a step after forming a metal member 7 inthe method according to Embodiment 9.

FIG. 41 is a sectional view of a step after removing a substrate 1 usedfor depositing the layered composite 10 in the method according toEmbodiment 9.

FIG. 42 is a sectional view of a step after forming a transparentelectrode on n-type nitride semiconductor layers (second conductivitytype layers) 2 subsequent to the removal of the substrate 1 fordepositing the layered composite 10, in the method according toEmbodiment 9.

FIG. 43 is a sectional view of a step after forming n pad electrodes andinsulating layers 4 subsequent to the formation of the transparentelectrode, in the method according to Embodiment 9.

FIGS. 44A to 44C are sectional views of steps for forming a frustumlayered composite according to Embodiment 9.

FIG. 45 is a sectional view of a nitride semiconductor light-emittingdevice according to a modification of Embodiment 9.

FIG. 46 is a sectional view of a nitride semiconductor light-emittingdevice according to a modification of Embodiment 9, different from thedevice shown in FIG. 45.

FIG. 47 is a sectional view of a nitride semiconductor light-emittingdevice according to Embodiment 10.

FIG. 48 is a sectional view of a nitride semiconductor light-emittingdevice according to modification 1 of Embodiment 10.

FIG. 49 is a sectional view of a nitride semiconductor light-emittingdevice according to modification 2 of Embodiment 10.

FIG. 50 is a plan view of a nitride semiconductor light-emitting deviceaccording to Embodiment 10.

FIG. 51 is a plan view of a nitride semiconductor light-emitting deviceaccording to modification 3 of Embodiment 10.

FIGS. 52A and 52B are schematic perspective views of the shape of astructured composite 10 according to the first aspect.

FIGS. 53A and 53C are schematic perspective views of the shape of thestructured composite 10 according to the first aspect; FIG. 53B is anenlarged perspective view of part (side surfaces 10 x and 10 y) of FIG.53A; and FIG. 53D is a schematic top view of FIG. 53A provided with asecond electrode (n electrode) 21.

FIG. 54A is a schematic sectional view of a light-emitting apparatusaccording to the fourth aspect (Embodiment 10); and FIG. 54B is anequivalent circuit diagram of the apparatus.

FIG. 55 is a schematic sectional view of a light-emitting apparatusaccording to the fourth aspect (Embodiment 11).

FIG. 56 is a schematic sectional view of a light-emitting apparatusaccording to the fourth aspect (Embodiment 11).

FIGS. 57A to 57D are schematic sectional views of irregular interfaces600 of a light-emitting device according to the present invention.

FIG. 58 is a schematic sectional view of a device structure of thelight-emitting device according to the present invention.

FIGS. 59A and 59B are schematic sectional views for describing theremoval of the substrate of the light-emitting device according to thepresent invention.

FIGS. 60A to 60E are schematic perspective views for describing thedevice structure and the electrode structure of the light-emittingdevice according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION First Aspect

In view of a first aspect of the present invention, the light-emittingdevice of the present invention has a protruding structured portiondisposed in at least part of the device, and more preferably in anoperational portion (current injection area of the device) of thedevice. The structured portion may be used for a non-operational portion(current non-injection area) of a device layered structure or othermembers, such as a light-transmissive member in the light-emittingdevice. Examples of the structured portion 10 are shown in FIGS. 53A to53D: A and C are schematic perspective views of the examples, and theother figures are a fragmentary enlarged view of FIG. 53A and a planeview showing the upper surface of the structured portion shown in FIG.53A.

For comparison with the first aspect, FIGS. 52A and 52B show anotherform of the structured portion 10. In FIG. 52A, the structured portionis formed in a frustum of a pyramid having a square lower surface 10 g.The corners of the structured portion are cut off along dotted lines 10x-1 and 10 x-2 to form a frustum of polygonal, as shown in FIG. 52B.Consequently, each side surface defining the periphery of the structuredportion has a width decreasing toward the upper surface from the lowersurface 10 g. Also, the sides defined by the periphery and a crosssection at a height of the structured portion, having a normal in theheight direction of the structured portion have a constant lengthproportion at any height. If such a protruding structured portionincludes a luminescent layer 4 inside, light reflects large from theperiphery at the sides of the luminescent layer and the other area ofthe periphery slightly reflect the light. In addition, the upper surfacecannot control the reflection sufficiently, and the intensity of thelight is reduced in the direction of the normal of the upper surface,accordingly. Also, the strength of reflection from the vicinity of theluminescent layer 4 is increased in comparison with the reflection fromthe other areas of the periphery. Consequently, light isdisproportionately emitted in a ring shape.

In addition, when an electrode is provided according to a second aspectdescribed later in a manufacturing process, the precision of theelectrode shape tends to be degraded, as designated by the dotted line21 m in FIG. 52B. This is because if the width of the chamfers of theprotrusion 10 is small on the upper surface side, a mask or other resistdoes not sufficiently reach the side surfaces, and consequently the maskoften protrudes in the lateral direction at the shoulders of thechamfers, as shown in the figure illustrating a state where a mask M1 isformed on the protrusion 10. In particular, if the length of the sidesof the upper surface 10 f is small, the mask protrudes notably, and theelectrode 21 m is formed in an unstable shape accordingly. The unstableshape of the electrode often brings about a serious problem in the casewhere the second aspect is applied, where the structure cannot ensure anarea sufficient to form the electrode.

Furthermore, if an electrode is formed on the upper surface 10 f, asshown in FIG. 52A, and current is injected to the electrode, the currentis liable to be nonuniform in the regions around the corners and shortersides of the upper surface.

The present invention is intended to overcome the above-describedproblems. Specifically, the invention provides a protruding structuredportion 10 having an inclined periphery which includes first sidesurfaces 10 x, each having a width or a curvature radius increasingupward. Thus, the shape of the cross section at a height of thestructured portion, for example, the proportion of the lengths of thesides defining the cross section, is varied large depending on theheight to exhibit a variety of shapes of the periphery viewed fromabove. As a result, nonuniformity in directivity of light can be reducedin the regions in the periphery from which light is reflected orextracted. Also, since the upper surface has large areas sufficient forcurrent injection in the corners, nonuniformity of current can bereduced. Furthermore, since the upper base of the side surface is longeror curved, the protrusion of the resist can be reduced and a structuredportion suitable for processing of devices or elements, such aselectrodes, can be provided. Thus, the resulting light-emitting devicecan exhibit superior reliability and mass-productivity.

The structured portion according to the first aspect can be formed byappropriately selecting the shape or thickness of the mask M1, forexample, by varying the thickness of the mask M1 or layering maskshaving different shapes, as shown in FIGS. 20A to 20C and 44A to 44C.

Preferably, the periphery includes second side surfaces 10 y having awidth decreasing from the lower surface 10 g toward the upper surface 10f, and the first side surfaces 10 x having a width decreasing in theopposite direction. In this instance, according to the shape of theupper surface, the side surface 10 y with a longer base (side 10 g-1) onthe lower surface 10 g side may be changed into such a shape as thesides 10 x-1 and 10 x-2 being the boundaries between the first and thesecond side surfaces disappear on the way from the lower base to theupper base, as shown in FIG. 53C; hence, the second side surface doesnot necessarily reach to the upper surface. Thus, the upper surface 10 fand the lower surface 10 g may have different shape, as defined by thedotted line 10 f and 10 g in FIG. 53C. The side surfaces may besufficiently curved at the upper surface side to be circular. The uppersurface 10 f and the lower surface 10 g are provided in desired verticalpositions of the structured portion. Preferably, the entirety of aprotrusion corresponding to the layered structure of a device definesthe structured portion of the present invention. More preferably, thedivergent first side surface having a width increasing toward the uppersurface may be curved outward to have a convex surface, thereby ensuringsuperior reflection and diffusion of light and precision of maskformation. The proportion of the lengths of the upper bases 10 f-x and10 f-1 or lower bases 10 g-x and 10 g-1 of the first side surface 10 xto the second side surface 10 y is not particularly limited. For forminga suitable shape of the protrusion, however, it is preferable that boththe upper base 10 f-x and the lower base 10 g-x of the first sidesurface be shorter than the upper base 10 f-1 and the lower base 10 g-1of the second side surface.

FIG. 53D is a plan view of an electrode, which is designated by thehatched area (electrode 21). The electrode is formed such that thecorners of the upper surface of the electrode are curved larger than thecurvature radius or the width of the corners (first side surfaces) ofthe structured portion, as designated by a dotted line (21 g-x); Hence,the surrounding electrode is curved larger than the corners 10 f-x atthe lower side of the structured portion 10. Thus, currentconcentration, which tends to occur in the corners of, for example, thestructured portion shown in FIG. 53C, can be reduced.

In the light-emitting device of the present invention (according to thefirst aspect, and the second and third aspects based on the firstaspect), the luminescent layer 4 is preferably disposed inside thestructured portion 10, as shown in FIGS. 53A to 53D, so that light iswell controlled. More preferably, the luminescent layer 4 is disposedbetween part of the first conductivity type layer 2 and the secondconductivity type layer 3. Still more preferably, a second electrode (anelectrode of the second conductivity type layer 3 or p electrode of thep-type layer) is provided on the upper surface. The periphery of thestructured portion in sectional view is not necessarily defined bystraight lines as shown in FIGS. 53A to 53D, and may be defined by acurved line. Also, the periphery may have a step or terrace 2 s, asshown in FIG. 58. The upper surface 2S of the jut of the periphery maybe provided with an electrode extending over the periphery below theupper surface.

Second Aspect

Embodiments of a nitride semiconductor light-emitting device accordingto the present invention (first aspect) will now be described withreference to the drawings.

Embodiment 1 Second Aspect

An nitride semiconductor light-emitting device according to Embodiment 1of the present invention includes: a layered portion 10 defining aluminescent region and having a periphery 10 a inclined inward; and nelectrode 21 in ohmic contact with an n-type contact layer 12 exposed atthe inclined periphery 10 a, as shown in FIGS. 1 and 2.

The layered portion 10 of the nitride semiconductor light-emittingdevice according to Embodiment 1 is formed by depositing a buffer layer11, an n-type contact layer 12, an n-type cladding layer 13, aluminescent layer 14, a p-type cladding layer 15, and a p-type contactlayer 16, in that order, on a sapphire substrate 1, to form a layeredstructure, as shown in FIG. 2, and subsequently by etching the layeredstructure to a shape (substantially square whose one corner is cut to anarc shape) in sectional view shown in FIG. 1.

The layers constituted of the layered portion 10 are formed of, forexample:

Buffer layer 11: GaN or AlGaN layer deposited at a low temperature of400 to 600° C.

N-type contact layer 12: Si-doped GaN (having a thickness of, forexample, 6 μm)

n-type cladding layer 13: n-type AlGaN

Luminescent layer 14: single- or multi-quantum well structure includingan undoped InGaN well layer (having a thickness of, for example, about30 Å)

P-type cladding layer 15: p-type AlGaN

P-type contact layer 16: Mg-doped GaN (having a thickness of, forexample, about 1,200 Å)

The etching for forming the layered portion 10 is performed until thesurface of the sapphire is exposed at the arc-shaped corner, in order toform an n electrode 21 on the exposed surface of the sapphire at thearc-shaped corner. In the present Embodiment 1, the surface of thesapphire substrate is exposed so as to surround the layered portion 10continuously with the sapphire surface exposed at the arc-shaped cornerfor the n-type electrode 21.

In Embodiment 1, the n electrode 21 is continuously formed from thesurface of the sapphire substrate 1 exposed at the corner of the layeredportion 10 to the periphery 10 a of the layered portion 10, and thusestablishes an ohmic contact with the n-type contact layer 12 exposed atthe periphery 10 a, as shown in FIGS. 1 and 2.

On the other hand, the p electrode includes an over-surface electrode 31and a p pad electrode 32. The over-surface electrode 31 is provided oversubstantially the entire surface of the p-type contact layer 16, whichis the uppermost layer of the layered portion 10, and the p padelectrode 32 is disposed on the over-surface electrode 31 in a regionopposing the n electrode 21 (opposing corner).

The n electrode 21 of the nitride semiconductor light-emitting device ofEmbodiment 1 having the above-described structure can extremely reducelight absorption. Accordingly, the nitride semiconductor light-emittingdevice can efficiently emit light.

In a known structure shown in FIG. 21, light emitted from theluminescent region leaks to an n type contact layer 512 between thesubstrate 1 and an n electrode 521, and the light repeatedly reflectfrom the upper surface of the substrate 1 and the rear surface of the nelectrode 121 (as schematically shown with reference numeral Y100 inFIG. 21). Thus, most of the light is absorbed by the n electrode 121 andcannot be extracted to the outside. On the other hand, in the presentinvention, the ohmic contact of the n electrode is established on thesurface 12 a of the n-type contact layer 12 exposed at the inclinedperiphery 10 a, thus preventing the n-type contact layer 12 fromtransmitting light (as schematically shown with reference numeral Y1 inFIG. 2). Thus, the conventional problem is overcome.

If emitted light is emitted through the substrate, light reflected fromthe inclined periphery 10 a of the layered portion 10 can also beemitted through the substrate. Thus, the light-emission efficiency canbe increased.

In order to reflect light efficiently at the inclined periphery 10 a forextraction of the light from the substrate, the inclination angle α ofthe periphery 10 a is, preferably, set at 60° or less, more preferably45° or less, taking it into account that the inclined periphery 10 a isgenerally covered with a SiO₂ protective layer.

The inclination angle α herein is defined as shown in FIG. 22, and ispreferably set so that the critical angle θc satisfies Sinθc=n_(S)/n_(G) (n_(G): refractive index of the active layer; n_(S):reflective index of the SiO₂ protective layer).

For example, in a light-emitting device emitting light having awavelength of 380 nm, the refractive index of Al_(x)Ga_(1-x)N for thelight having the wavelength of 380 nm is 2.15 to 2.80 when X lies in therange of 1 to 0. In this instance, when the refractive index is 2.80,the critical angle θc comes to a minimum of about 30°.

By setting the critical angle θc at 30° or more, that is, by setting theinclination angle α at 60° or less, at least the strongest lightpropagated parallel to the semiconductor layers can be reflectedtotally.

As described above, by setting the inclination angle α at 60° or less,the strongest light propagated parallel to the semiconductor layers isreflected totally, and consequently, the light extraction efficiency canbe increased. However, some rays of the light propagating in thesemiconductor layers do not run parallel to the layers. In order tototally reflect light, including these rays, it is more preferable thatthe inclination angle α be set at 45° or less.

In addition, the projected length W being the inclination length L ofthe inclined periphery 10 a viewed from above is preferably 10 μm ormore from the viewpoint of the formation of the n electrode on theinclined periphery 10 a.

Embodiment 1 has described the structure in which the ohmic contact ofthe n electrode 21 with the n-type contact layer 12 is established at acorner of the layered portion. However, the n electrode preferablyformed so as to surround the layered portion 10, as shown in FIGS. 3 and4, in which the n electrode is designated by reference numeral 22. Thisstructure allows uniform current injection to the entire luminescentregion, and thus light can be efficiently emitted.

Embodiment 2 Second Aspect

A nitride semiconductor light-emitting device according to Embodiment 2of the present invention has a circular layered portion 110 defining aluminescent region, as shown in FIG. 5. In the nitride semiconductorlight-emitting device of Embodiment 2, the n electrode 23 is broughtinto ohmic contact with the n-type contact layer 12 exposed at theperiphery 110 a inclined inward of the layered portion 110, as inEmbodiment 1.

In the nitride semiconductor light-emitting device according toEmbodiment 2, the layered structure (semiconductor layers) of layeredportion 110 is formed in the same manner as the light-emitting device ofEmbodiment 1, and the etching for forming the layered portion 110 isperformed until the sapphire surface is exposed.

The p electrode in Embodiment 2 includes an over-surface electrode 33and a p pad electrode 34. The over-surface electrode 33 is provided oversubstantially the entire circular surface of the p-type contact layer16, which is the uppermost layer of the layered portion 110, and the ppad electrode 34 is disposed in the center of the over-surface electrode33.

The over-surface electrode 33, the p pad electrode 34, and the circularlayered portion 110 are concentrically disposed.

The nitride semiconductor light-emitting device of Embodiment 2 havingthe above-described structure produces the same effect as thelight-emitting device of Embodiment 1.

Specifically, light absorption by the n electrode 23 can be extremelyreduced, and accordingly, the device can efficiently emit light. Inaddition, light reflected from the inclined periphery 110 a of thelayered portion 110 can also be emitted through the substrate, and thusthe light-emission efficiency can be increased.

Furthermore, since the n electrode 23 of Embodiment 2 surrounds thelayered portion 110, as shown in FIG. 5, current can be uniformlyinjected into the entire luminescent region, and thus light can beefficiently emitted.

Embodiment 3 Second Aspect

A nitride semiconductor light-emitting device according to Embodiment 3of the present invention also has a layered portion 110 formed in acircular shape, but is different from that of the nitride semiconductorlight-emitting device of Embodiment 2 in the following respects, asshown in FIGS. 6 and 7.

Specifically, the p-type contact layer of the nitride semiconductorlight-emitting device of Embodiment 3 is provided with a transparentlight-transmissive ohmic electrode 33 a on its surface, and a p padelectrode 34 is formed on the ohmic electrode 33 a.

Also, in the nitride semiconductor light-emitting device of Embodiment3, an n electrode 24, which is to be brought into ohmic contact with ann-type contact layer at an inclined periphery 110 a, is continuouslyformed on the side surfaces and the rear surface of the substrate 1, asshown in FIG. 7.

Other components than the light-transmissive ohmic electrode 33 a andthe n electrode 24 are formed in the same manner as in Embodiment 2.

The nitride semiconductor light-emitting device of Embodiment 3 cantransmit light emitted from the layered portion 110 to the outsidethrough the light-transmissive electrode 33 a, consequently producingthe following effects.

Specifically, light absorption by the n electrode 24 can be extremelyreduced, and accordingly, the nitride semiconductor light-emittingdevice can efficiently emit light. The light is reflected from the nelectrode 24 formed on the side surfaces and rear surfaces of thesubstrate and emitted through the light-transmissive ohmic electrode 33a. Thus, the light-emission efficiency can be increased.

Furthermore, since the n electrode 24 of Embodiment 3 surrounds thelayered portion 110, as shown in FIG. 6, current can be uniformlyinjected into the entire luminescent region, and thus light can beefficiently emitted.

Although, in the nitride semiconductor light-emitting device ofEmbodiment 3, the entire substrate is covered with the n electrode 24,the form of the present invention is not limited to this. For example,as shown in FIG. 8, the substrate 1 may be covered with anotherelectrode 26 formed of a different metal from the n electrode 25.

Such a structure also produces the same effects as Embodiment 3, andfurther produces the following effects.

Specifically, the n electrode 25 is made of a metal capable ofestablishing a good ohmic contact with the n-type contact layer, and theelectrode 26 covering the substrate 1 is made of a suitable metal fordesired functions.

For example, if the device is mounted by soldering the rear surface ofthe substrate 1, the material of the electrode 26 is selected fromheat-resistant materials, or if good light reflection is particularlyrequired, a metal having a high reflectance is selected.

Embodiment 4 Second Aspect

A nitride semiconductor light-emitting device according to Embodiment 4of the present invention has a rectangular layered portion 111 defininga luminescent region, as shown in FIG. 9.

Specifically, in the nitride semiconductor light-emitting device ofEmbodiment 3, an over-surface electrode 35 and a p pad electrode 36 areformed in that order on the surface of the p-type contact layer.

As shown in FIG. 9, an n electrode 27 brought into ohmic contact withthe n-type contact layer at the inclined periphery 111 a of therectangular layered portion 111 extends from the surface of thesubstrate to the n-type contact layer (exposed at the inclined periphery111 a).

The layered portion in Embodiment 4 has the same layered structure asthat in Embodiments 1 to 3.

The nitride semiconductor light-emitting device of Embodiment 4 havingthe above-described structure produces the same effect as thelight-emitting devices of Embodiments 1 to 3.

Although, the n electrode 27 of the nitride semiconductor light-emittingdevice shown in FIG. 9 is disposed so as to establish an ohmic contactwith the n contact layer at a side of the layered portion 111,Embodiment 4 may provide another form in which the n electrode, which isdesignated by reference numeral 28 in FIG. 10, is disposed so as toestablish an ohmic contact with the n contact layer at all the sides ofthe layered portion 111. Consequently, current can be uniformly injectedinto the entire luminescent region, and thus light can be efficientlyemitted.

Embodiment 5 Second Aspect

A nitride semiconductor light-emitting device according to Embodiment 5includes a plurality of layered portions 210 (18 layered portions inFIGS. 11 and 12), as shown in FIGS. 11 and 12, to have a largeluminescent area. This structure can increase the occupancy of theluminescent region in the entire area of the device, and thus light canbe uniformly emitted over entire area of the luminescent layer.

FIG. 11 is a plan view mainly showing a form of the n electrode 221,omitting p bonding electrodes 251 and p connecting electrodes 261; FIG.12 is a plan view showing another form of the n electrode, including thep bonding electrodes 251 and the p connecting electrodes 261. FIG. 13 isa sectional view taken along line D-D′ in FIG. 12.

The purpose in forming the luminescent region with a plurality ofportions is to eliminate the disadvantage that a luminescent regionconstituted of a non-separated portion with a large area reduces currentin a region distant from the electrode and degrades the luminousefficiency. However, if the luminescent region is constituted of aplurality of portions, the area of the electrodes connecting theportions of the luminescent region is increased, and it becomesdifficult to secure the area required for the luminescent region. Also,if a plurality of the known devices having the structure shown in FIG.21 are arranged, light is repeatedly reflected to be absorbed by the nelectrode while traveling through the n-type contact layer, and theluminous efficiency is reduced. On the other hand, the nitridesemiconductor light-emitting device of Embodiment 5 has the n electrodesin ohmic contact with the n-type contact layers, on the inclinedperipheries. Thus, the area which the n electrode requires can bereduced to secure the area of the luminescent region, and the nelectrode is prevented from absorbing light.

The nitride semiconductor light-emitting device of Embodiment 5 can morereduce the absorption by the over-surface electrode on the p side thanthe known device.

Specifically, in the known device having a large-area luminescent regionconstituted of a single portion, as shown in FIG. 23B, light coming intothe p over-surface electrode at the critical angle or more is repeatedlyreflected at the p over-surface electrode and the boundaries between thesemiconductor layer and the substrate, so that considerable part of thelight is absorbed by the p over-surface electrode.

If the luminescent region is composed of a plurality of portions but theperipheries of the portions are not inclined, the light coming into thep over-surface electrode at the critical angle or more is emitted fromthe peripheries substantially perpendicular to the substrate to reenterthe adjacent portions of the luminescent region at a high probability,as shown in FIG. 23C. Consequently, the percentage of absorption by thep over-surface electrode is increased.

In contrast, the portions of the luminescent region of the nitridesemiconductor light-emitting device of Embodiment 5 each have theincline periphery. Therefore, light can be emitted to the outsidewithout reentering the adjacent portions of the luminescent region (theprobability that the light reenters the adjacent portions can bereduced), as designated by arrow A2 in FIG. 23B if light is emittedthrough the substrate, or as designated by arrow A3 if light comes outfrom the electrode side. Thus, the percentage of absorption by the pover-surface electrode 31 can be reduced.

In addition, the layered portions 210 constituting the luminescentregion, in the nitride semiconductor light-emitting device of Embodiment5, have a hexagonal shape, and they are arranged such that the areabetween the layered portions is a minimum (FIGS. 11 and 12). InEmbodiment 5, the spaces between the adjacent layered portions 210 areetched to such a depth as to reach the surface of the substrate (FIG.13), and thus the plurality of the layered portions 210 are completelyseparated from each other. The intervals between the adjacent layeredportions 210 are set at, for example, 10 μm.

Furthermore, in Embodiment 5, an n electrode 221 is provided so as tocome into ohmic contact with n-type contact layers exposed at theperipheries of the layered portions 210, each of which has the sameinclined periphery 210 a as that of Embodiment 1 and other embodiments.

In Embodiment 5, the n electrode 221 is integrally formed so as tosurround each layered portion 210, as shown in FIG. 11.

In Embodiment 5, the over-surface electrode 231 is formed oversubstantially the entire surface of the p-type contact layer of eachlayered portion 210, and the pad electrode 232 is disposed in the centerof the over-surface electrode 231. Then, an insulating layer 271 havingopenings over the p pad electrodes 232 covers the entire device.Connecting electrodes 261 (whose one end is connected to a p bondingportion) for connecting the p pad electrodes 232 are formed on theinsulating layer 271. The insulating layer 271 also has openings forexposing the bonding portions 241 of the n electrode 221.

As described above, the nitride semiconductor light-emitting device ofEmbodiment 5 includes the hexagonal layered portions 210 constitutingthe luminescent region, arranged so that the area between the layeredportions 210 comes to a minimum, and the n electrode on the inclinedperipheries of the layered portions 210. Thus, the area of theluminescent region can be increased.

This structure allows the luminescent region to be divided into asuitable number of portions to emit light efficiently while suppressingthe increase of the area for forming the n electrode. Consequently, theportions of the luminescent region can emit light efficiently withoutreducing the area of the luminescent region, and thus a large-arealight-emitting device exhibiting a high luminance can be achieved.

The nitride semiconductor light-emitting device of Embodiment 5 may emitlight through the substrate. Alternatively, a transparent electrode maybe used as the over-surface electrode to emit light through thesemiconductor. In either case, since the light emitted from theluminescent layer propagates to both the substrate and the p-typesemiconductor, it is preferable that a reflection layer be provided onthe side opposite to the light-emitting side. Thus, the luminousefficiency can be increased.

FIG. 14 shows another nitride semiconductor light-emitting deviceaccording to Embodiment 5, which further includes a second connectingelectrode 262 for connecting the connecting electrodes 261. The secondconnecting electrodes 262 are intended to prevent current injection fromdecreasing in the layered portions 210 distant from the p bondingelectrodes 251, and to make the emission intensities of the layeredportions uniform.

If light is emitted through the semiconductor layers, however, thesecond connecting electrodes 262 block the light. Therefore, the secondelectrodes are particularly suitable for devices emitting light throughthe substrate.

FIG. 15 shows an modification of the connecting electrodes suitable forthe device emitting light through the semiconductor layer side. In thismodification, the first connecting electrodes 263 connecting to the pbonding electrodes 251 are disposed between the layered portions 210, onthe n electrode with an insulating layer therebetween, preventingcontinuity with the n electrode. Since the first connecting electrodes263 are not disposed over the layered portions, light is not blocked bythe layered portions. The first connecting electrodes 263 are connectedto the p pad electrodes of the layered portions 210 with secondconnecting electrodes 264. In this instance, each p pad electrode 232 isconnected to the first connecting electrode 263 with one secondconnecting electrode 264.

FIGS. 16A and 16B show preferred structures of the electrodes when lightis emitted through the substrate.

The nitride semiconductor light-emitting device shown in FIG. 16A has anelectrode layer 265 covering the plurality of layered portions,separated by the insulating layer 271, instead of the connectingelectrodes 261 (including the p bonding electrodes) used in Embodiment 5(FIG. 12).

The electrode layer prevents the leakage of light from the uppersurfaces and inclined peripheries of the layered portions (reflectslight at the upper surface and inclined peripheries), so that light canbe efficiently emitted. Alternatively, a connecting electrode 265 may beprovided on a mounting surface or mounting base 10300, so that theplurality of structured portions 210 (10) can simultaneously emit lightwithout solid intersection of the positive and negative electrodes.Also, in this structure, a protective layer, a reflection layer, atransmissive layer, a light-transforming member, and so forth can beprovided around the structured portions to make efficient use of space.Furthermore, leakage resulting from the solid intersection of the wiringcan be overcome. Thus, a highly reliable light-emitting device can beachieved.

Although the nitride semiconductor light-emitting device of Embodiment 5has hexagonal layered portions 210, the layered portions may be ofrectangular, square, circular, or other shape.

FIG. 24 is a plan view of a modification in which the layered portions410 are of square. In this modification, the p bonding portions 451 aredisposed on the layered portions 410 in two corners of the device, andthe connecting electrodes 461 connected to the p bonding portions 451connect the p pad electrodes of the layered portions 410. In order toprevent the continuity between the n electrode and the connectingelectrodes 461, an insulating layer is provided on the n electrodebetween the layered portions 410.

Also, the n electrode 421 is integrally formed so as to surround eachlayered portion 410 and to come into ohmic contact with the n-typecontact layers exposed at the inclined peripheries 410 a of the layeredportions 410. Part of the n electrode 421 serves as an n pad electrode441.

The device may be mounted on a mounting base (protection element) 10300by flip chip bonding in such a manner that the electrode side of thedevice opposes the board, as shown in FIGS. 33A and 33B showing amodification of FIG. 24. In FIG. 33A, the region of the mounting basehidden by the substrate, as well as the exposed regions is designated bysolid lines. In this figure, the first side surface and the second sidesurface of the structured portion in the first aspect of the presentinvention described above are provided. Specifically, the curvatureradius of the corners of the lower surface of the layered portion issmaller than that of the upper surface (the surface of the p-typelayer), and the n electrode is formed so as to have larger curves aroundthe structured portions than the curvature radius of the corners of thestructured portions. The n electrode 721 (21) covers some 710 x of theplurality of structured portions 710 (10) up to the upper surfaces toserve as bonding surfaces for bonding 11400 a, as shown in FIG. 33B.Thus, the device can be mounted on a mounting base or the like in such amanner that the vertical position of the bonding surfaces is alignedwith the vertical position of the p electrodes of the other structuredportions. The structured portion 710 x can serve for a non-operationalportion which does not work as the device.

Embodiment 6 Second Aspect

FIG. 17 is a plan view of the arrangement of a nitride semiconductorlight-emitting device according to Embodiment 6, and FIG. 18 is a planview of one of the layered portions 310. FIG. 19A is a sectional viewtaken along line E-E′ in FIG. 18; FIG. 19B is a sectional view takenalong line F-F′ in FIG. 18.

In the nitride semiconductor light-emitting device of embodiment 6, thelayered portions 310 are formed in a circular shape, and arranged suchthat their centers are aligned in a matrix manner. The layered structureof each layered portion 310 is the same as that of other embodiments,and its periphery is inclined inward (inclined periphery 310 a), and thesection of the layered portion has a trapezoidal shape whose upper sideis defined as the upper base, as shown in FIGS. 19A and 19B.

The n ohmic electrode 321 a of each layered portion 310 is formed on theentire circumference of the inclined periphery 310 a so as to come intoohmic contact with the n contact layer exposed at the surface of theinclined periphery 310 a. In addition, n connecting pad electrodes 321 bare disposed on the substrate between the layered portions 310, and then ohmic electrode 321 a of each layered portion 310 is connected to fouradjacent n connecting pad electrodes 321 b.

Specifically, in the nitride semiconductor light-emitting device ofEmbodiment 6, the n electrode 321 includes the n ohmic electrodes 321 aand the n connecting pad electrodes 321 b.

Also, the over-surface electrode 331 is provided over substantially theentire upper surface (upper surface of the p contact layer) of eachlayered portion 310, and a circular p pad electrode 332 is formed in thecenter of the over-surface electrode 331.

After forming the n ohmic electrodes 321 a, n connecting pad electrodes321 b, over-surface electrodes 331, and p pad electrodes 332 asdescribed above, an insulating layer 371 is formed to cover the entiredevice except the upper surfaces of the connecting pad electrodes 321 b,their surroundings, and the p pad electrodes 332. Then, p connectingelectrodes 361 are formed to connect the p pad electrodes 332 of thelayered portions 310 to each other. The p connecting electrode 361includes a pad connecting portion 361 b connected to the upper surfaceof the p pad electrode 332 and a connecting portion 361 a connecting thepad connecting portion 361 b to another pad connecting portion.

The nitride semiconductor light-emitting device having theabove-described structure according to Embodiment 6 can prevent theelectrodes from absorbing light and exhibit increased light extractionefficiency, as in Embodiment 1.

In order to examine the light extraction efficiency of the nitridesemiconductor light-emitting device of Embodiment 6, the followingcomparative examinations were conducted.

Nine (3×3) layered portions 310 were formed to constitute a nitridesemiconductor light-emitting device of Embodiment 6, as shown in a planview FIG. 25, and the extraction efficiency of the nitride semiconductorlight-emitting device was compared with that of a light-emitting devicehaving a single layered portion 310 (shown in a plan view FIG. 28).

For the measurement of extraction efficiency, a test piece of thelight-emitting device was die-bonded in a cup integrally having anegative terminal. The n pad electrode was connected to the negativeterminal T2 with a bonding wire W21, and the p pad electrode wasconnected to a positive terminal T1 with a bonding wire W32. Then, thequantity of extracted light was measured relative to the quantity ofemitted light.

As a result, the device having the nine layered portions 310 ofEmbodiment 6 (FIG. 25) exhibited an extraction efficiency of 86% whenthe extraction efficiency of the light-emitting device having the singlelayered portion 310 (FIG. 28) was assumed to be 100.

On the other hand, a light-emitting device (having nine layeredportions) shown in FIG. 26 prepared as a comparative example exhibited aextraction efficiency of 71% when the extraction efficiency of alight-emitting device having a single layered portion shown in FIG. 29Awas assumed to be 100.

In the measurements, the extraction efficiencies of the light-emittingdevice having the single layered portion 310 (FIG. 28) and thelight-emitting device having the single layered portion shown in FIG.29A were substantially the same.

The layered portions of the light-emitting device of the comparativeexample have the same layered structure as in Embodiment 6, and areformed in a substantially square shape in plan view. In each layeredportion, the n electrode 521 is provided on the surface of the n-typecontact layer exposed at one corner of the layered portion. The p ohmicelectrode 531 is provided over substantially the entire surface of thep-type contact layer, and the p pad electrode 532 is formed on the pohmic electrode 531 in the corner opposing the n electrode 521. In thedevice shown in FIG. 26, the spaces between the adjacent layeredportions are etched until the sapphire substrate is exposed so that thelayered portions are completely separated from each other. The peripheryof each layered portion is substantially perpendicular to the uppersurface of the sapphire substrate.

As described above, it has been confirmed that the nitride semiconductorlight-emitting device having the plurality of layered portions accordingto Embodiment 6 has a higher extraction efficiency than the nitridesemiconductor light-emitting device of the comparative example, which isalso of cluster type.

FIG. 27 shows a device of another comparative example in which thespaces between the layered portions are not etched until the sapphiresubstrate is exposed and the n-type contact layer remains. The lightextraction efficiency of the device of this comparative example shown inFIG. 27 was 68% when the extraction efficiency of the light-emittingdevice having the single layered portion shown in FIG. 29B was assumedto be 100.

In the measurement, the extraction efficiencies of the device shown inFIG. 29A and the device shown in FIG. 29B were substantially the same.

As described above, the light-emitting devices having a plurality oflayered portions of both the comparative examples exhibited lowerextraction efficiencies than the extraction efficiency of thelight-emitting device of Embodiment 6.

The nitride semiconductor light-emitting device of Embodiment 6 producesthe same effects as the light-emitting device of Embodiment 5, andfurther has the following characteristic features.

Since a device including a desired number of layered portions can be cutout to a desired size from a wafer having layered portions 310 on anas-needed basis, devices with desired sizes can be produced using asingle pattern.

In this instance, the n connecting pad electrode 321 b and the padconnecting portion 361 b in any position may be used as the bondingelectrodes.

The nitride semiconductor light-emitting devices of the above-describedembodiments may emit light through the substrate or through thesemiconductor side. In either case, it is preferable that a reflectionlayer be provided on the side opposite to the light-emitting side. Inthe structures shown in FIGS. 7, 8, 16A and 16B, the n electrode 24,electrode 26, or electrode 265 can be used as a reflection layer, asdescribed above. In the other structures, it is preferable that areflection layer be additionally provided. The reflection layer may beformed of a metal having a high reflectance, or a dielectric multilayerfilm. If a dielectric multilayer film is used, the insulating layer 271in FIG. 13, for example, is given reflectivity in addition to insulationperformance.

Embodiment 7 Second Aspect

FIG. 31 is a plan view of the arrangement of a nitride semiconductorlight-emitting device according to Embodiment 7. In the nitridesemiconductor light-emitting device of embodiment 7, the layeredportions 310 are formed in a circular shape, and arranged on a substratesuch that their centers lie at vertices of hexagons to form a hexagonalgrid. The layered structure of the layered portions 610 is the same asin other embodiments, and the peripheries are inclined inward.

The n ohmic electrode 621 a of each layered portion 610 is formed on theentire circumference of the inclined periphery so as to come into ohmiccontact with the n contact layer exposed at the surface of the inclinedperiphery. In addition, an n connecting pad electrode 621 b is disposedin the center of each hexagon defined by six layered portions 610 of thehexagonal grid, and the n ohmic electrode 621 a of each layered portion610 is connected to three adjacent n connecting pad electrodes 321 b.

Specifically, in the nitride semiconductor light-emitting device ofEmbodiment 7, the n electrode includes the n ohmic electrodes 621 a andthe n connecting pad electrodes 621 b.

Also, the over-surface electrode is provided over substantially theentire upper surface (upper surface of the p contact layer) of eachlayered portion 610, and a circular p pad electrode 632 is formed in thecenter of the over-surface electrode. The p pad electrodes 632 of thelayered portions 610 are connected to each other with p connectingelectrodes 661.

The n electrode including the n ohmic electrodes 621 a and the nconnecting pad electrodes 621 b is electrically insulated from the pelectrode including the over-surface electrodes 631, the p padelectrodes 632, the p connecting electrodes 661, as in Embodiment 6.

In the above-described nitride semiconductor light-emitting device ofEmbodiment 7, two layered portions are assigned for each n connectingpad electrode 621 b. This structure can increase the area of theluminescent region as a whole in comparison with the structure ofEmbodiment 6, in which one layered portion is assigned for each nconnecting pad electrode.

The layered portion arrangement as in Embodiment 7 can be divided intoportions having an outside shape of triangle, hexagon, rhombus,parallelogram, or the like. In this instance, the crystallographic axisof GaN crystals can be aligned with the direction of scribing lines.Thus, the yield in a step of dividing can be increased.

A process for forming the layered portion having an inclined peripheryof the nitride semiconductor light-emitting devices of theabove-described embodiments will now be described.

In the process, the buffer layer 11, the n-type contact layer 12, then-type cladding layer 13, the luminescent layer 14, the p-type claddinglayer 15, and the p-type contact layer 16 are deposited in that order onthe sapphire substrate 1 to form a layered structure, and a mask M1having a trapezoidal shape in sectional view is formed on the layeredstructure, as shown in FIG. 20A.

Then, the layered portion is etched from above the mask M1 by reactiveion etching. Here the mask is also gradually etched simultaneously withthe etching of the layered portion. The region designated by referencenumeral R1 between the broken line and the solid line in FIG. 20B isremoved.

The etching is continued until the surface of the substrate is exposedaround the layered portion 10 (FIG. 20C).

Thus, the layered portion 10 having an inclined periphery 10 a and ashape according to the shape of the mask M1 is formed.

In the process, the shape of the mask M1 is determined in considerationof the RIE rates of the mask material and the nitride semiconductormaterials. Thus, the layered portion having a desired, inclinedperiphery can be formed.

For example, a mask M1 having a periphery protuberating outward leads toa layered portion having a convex surface protuberating outward.

By forming the inclined periphery to a convex protuberating outward,light can be concentrated to emit if it is emitted through thesubstrate.

The above-described embodiments have been described using devices whichare etched around the layered portion to such a depth as to reach thesurface of the substrate. However, the n-type semiconductor layer mayremain with a thickness capable of preventing the transmission of lightbecause, in the present invention, it is important to prevent light frombeing transmitted to the region around the layered portion.

Third Aspect

Embodiments of a nitride semiconductor light-emitting device accordingto a third aspect will now be described with reference to the drawings.

Embodiment 8 Third Aspect

A nitride semiconductor light-emitting device according to Embodiment 1has nitride semiconductor layers defining the luminescent region whichare partially embedded into a metal member 7, and the metal member 7supports the entire light-emitting device.

In the nitride semiconductor light-emitting device of Embodiment 8, aluminescent layer 4 is disposed between a n-type nitride semiconductorlayer 2 and a p-type semiconductor layer 3 to define a doubleheterostructure luminescent region. The p-type nitride semiconductorlayer, the luminescent layer, and part of the n-type nitridesemiconductor layer are formed in frustum shapes. In other words, thethird aspect of the present invention leads to a device having a frustumlayered composite including at least a p-type nitride semiconductorlayer and a luminescent layer. A p-type ohmic electrode 36 is formedover substantially the entire surface of the p-type nitridesemiconductor layer 3 of the layered composite 10, and an insulatinglayer 72(5) covering the surroundings of the p-type ohmic electrode 36,the inclined periphery 10 a of the layered composite 10, and the n-typesemiconductor layer 2 (8 b) continuing to the periphery 10 a.

The layered composite 10 having this structure is embedded into a metalmember 7 to be supported. In this structure, the insulating layer 72separates the periphery of the layered composite 10 from the metalmember 7, and the surface having the p-type ohmic electrode 36 of thelayered composite 10 opposes the metal member 7 with the p-type ohmicelectrode 36 therebetween. In addition, a transparent electrode 21 isprovided on one surface of the opposing two surfaces of the p-typenitride semiconductor layer 2, opposite to the layered composite 10, andan n pad electrode 29 is provided on part of the transparent electrode21.

In the nitride semiconductor light-emitting device of Embodiment 8having the above-described structure, light emitted from the luminescentlayer 4 of the layered composite 10 comes out through the transparentelectrode 21 on the opposite side of the metal member 7.

A process for manufacturing the nitride semiconductor light-emittingdevice of Embodiment 8 will now be described.

In the process, first, the n-type nitride semiconductor layer 2, theluminescent layer 4, and the p-type nitride semiconductor layer 3 aredeposited, in that order, on the sapphire substrate 1 with, for example,a buffer layer (not shown) between the sapphire substrate 1 and then-type semiconductor layer 2, as shown in FIG. 35.

Then, the frustum layered composites 10 are formed by etching the layersuntil the n-type nitride semiconductor layer is exposed between thedevices (FIG. 36).

The etching for the frustum layered composites 10 can be performed usinga mask formed in a predetermined frustum, and the layered composites areformed in a frustum shape according to the shape of the mask.

More specifically, first, a mask M1 having a trapezoidal shape insectional view is formed on the p-type nitride semiconductor layer 3, asshown in FIG. 44A. The mask M1 is made of a material capable of beingetched at a constant rate by reactive ion etching.

Then, the semiconductor layers (p-type nitride semiconductor layer 3,luminescent layer 4, and n-type nitride semiconductor layer 2) on thesapphire substrate 1 are etched from above the mask M1. The mask M1 isgradually removed together with the semiconductor layers in this etchingstep. The region designated by reference numeral R1 between the brokenline and the solid line in FIG. 44B is removed.

The etching is continued until the surface of the n-type nitridesemiconductor layer 2 is exposed around the layered portions 10 (FIG.44C).

Thus, the frustum layered portions 10 are formed according to the shapeof the mask M1.

In the process, the shape of the mask M1 is determined in considerationof the RIE rates of the mask material and the nitride semiconductormaterials. Thus, the layered portions 10 having a desired frustum shapecan be provided.

The layered composites 10 may be formed by other dry etching thanreactive ion etching, such as reactive ion beam etching or ion milling.

For the formation of the frustum layered portions 10, isotropic etching,such as wet etching, may be adopted to take an advantage of an undercut(side-etching) phenomenon. The undercut facilitates the formation offrustum, but the processing precision is inferior to the processing bythe above-mentioned dry etching.

The inclination angle of the periphery 10 a of the layered composite 10(angle formed with the main surface of the sapphire substrate 1) ispreferably set in the range of 30° to 80°, and more preferably at 45°,from the viewpoint of increasing the efficiency in extracting lightemitted through the n-type nitride semiconductor layer.

The frustum may be in a frustum of a cone, a pyramid (tetragonalpyramid, hexagonal pyramid, or the like), or other shape.

After forming the frustum layered portions 10 as above, the p-type ohmicelectrode 36 is formed over substantially the entire surface of theupper base (surface of the p-type nitride semiconductor layer 3) of eachlayered portion 10.

The upper base herein refers to a surface with a smaller width of theopposing parallel surfaces of the frustum; the lower base of the layeredcomposite 2, the other surface with a larger width.

Although the p-type ohmic electrode 36 may be made of Ni/Au, Ni/Pt, orPd/Pt, the p-type ohmic electrode 36 is preferably constituted of, forexample, Rh/Au or Rh/Pt so that the Rh layer comes into contact with thep-type nitride semiconductor layer 3. By providing the Rh layer as afirst layer in contact with the p-type nitride semiconductor layer 3,the p-type ohmic electrode 36 is prevented from separating from thep-type nitride semiconductor layer 3 after forming the metal member 7.

The combinations of the constituents using “/” mean that the metalantecedent to the “/” is the first layer in contact with the p-typenitride semiconductor layer 3, and that the metal following the “/” is asecond layer on the first layer.

After the formation of the p-type ohmic electrode 36 on the p-typenitride semiconductor layer of each layered composite 10, the insulatinglayer 72(5) is formed over the entire substrate except the central area(other than the surroundings) of the p-type ohmic electrode 36, as shownin FIG. 38.

While the insulating layers 72, 73, and 5 are suitably formed of aninorganic insulating film, such as SiO₂, TiO₂, Al₂O₃, Si₃N₄, or ZrO₂, anorganic insulating film may be used.

Then, wiring electrodes 62 are formed between the layered portions 10 asrequired (FIG. 39).

Subsequently, a reflection later 62(6) is formed. The reflection layer 6is made of a light-reflective material, such as Ag, Pt, Rh, or Al. For alight-emitting device including a plurality of the layered portions, thereflection layer 6 may double as the wiring electrode. In particular,since the reflection layer is provided so as to oppose the inclinedperipheries of the frustum layered composites, the efficiency in use oflight can be dramatically increased.

The insulating layer 5 (72, 73) may double as the reflection layer.

Materials of the insulating layer serving as the reflection layerinclude SiO₂, TiO₂, Al₂O₃, Ta₂O₅, ZrO₂, Nb₂O₅, and Y₂O₃. Preferably, theinsulating layer 5 has a multilayer structure in which two materialshaving different refractive indices selected from these materials arealternately deposited. For example, 10 to 20 layers of a combination ofTiO₂/SiO₂ are deposited on top of one another to define a multilayerreflection layer.

Then, the metal member 7 is formed over the entire surface by, forexample, plating (FIG. 40). In the present invention, the metal member 7is principally intended to support the light-emitting device after thesapphire substrate 1 is removed in a subsequent step. The thickness ofthe metal member 7 must be large (preferably 50 μm or more, morepreferably in the range of 100 to 200 μm).

In the present invention, in order to achieve the primary function ofthe metal member 7, it may be formed of various metals, such as Ti, Ag,Al, Ni, Pt, Au, Rh, Cu, and W.

In Embodiment 8, the metal member 7 needs to have high adhesion to thereflection layer 6. If there is no reflection layer 6, the metal member7 is required to have adhesion to the insulating layer 5 (73) and thep-type ohmic electrode 36, particularly to the insulating layer 5 (73).For such a case, materials having superior adhesion to the insulatinglayer 5 (73) made of the above-described materials include Ti, W, Al,and Ni.

If the metal member 7 is formed of a reflective material, the reflectionlayer 6 may be omitted. Such metals include Ag, Al, Pt, and Rh.

In the present invention, the metal member 7 may function to reflectlight in addition to its primary function. In this instance, the metalmember 7 may be defined by a plurality of layers having respectivefunctions. For example, the metal member 7 includes a first metal filmas an underlayer, having a high reflectance for emitted light andsuperior adhesion to the insulating layer 5, p-type ohmic electrode 36,and the like; and a second metal film capable of having a largethickness on the first metal film.

Since the metal member 7 needs to have a relatively large thickness, itis preferably formed by electroless plating having high deposition speedor electroplating.

Specifically, electroplating, such as of Ni, Cu, Al, or Au, orelectroless plating, such as of Ni or Cu, may be applied.

In particular, electroless Ni plating is suitable because it can give ahigher strength than the strength of Au, Cu, and Ag to reduce warpage ofwafers, and because it does not require any electrical contact. Inaddition, Ni is superior in uniformity of the plating layer, depositionspeed, solder wettability, bump strength, and corrosion resistance.

Then, the sapphire substrate 1 is removed by exposing the substrate 1 toa laser beam, as shown in FIG. 41. Since the relatively thick metalmember 7 has been provided up to this stage, the substrate 1 may beremoved by various techniques, such as grinding and etching, in additionto laser beam exposure.

The surface of the n-type nitride semiconductor layer 2 exposed byremoval of the substrate is covered with a n-type electrode 21 (8) (FIG.42). The n-type electrode 21 (8) may be formed of W/Al, V/Al, W/Pt/Au,ZnO, ITO, Mo, or the like. ZnO and ITO are suitable for increasing thelight extraction efficiency, and ITO is also advantageous because of itsavailability.

For an ITO transparent electrode 21 (8), heat treatment is preferablyapplied to reduce the resistance. Preferred heat treatment temperatureis 100 to 500° C., and more preferably 200 to 400° C.

Then, n pad electrode 29 is provided to each layered composite 10, andan insulating layer 72 (5) is formed to cover the peripheries of the npad electrodes 29 and the transparent electrode 21 (8).

Subsequently, the wafer is divided between the layered portions intolight-emitting devices.

In the present invention, the division into devices is performed awayfrom the inclined peripheries 10 a of the layered composites 10 so thatthe inclined periphery 10 a is away from the periphery of the resultingdevice after division.

Since the nitride semiconductor light-emitting device according toEmbodiment 8 of the present invention is cut out along positionsseparate from the inclined periphery 10 a of the layered composite 10,the interface of the PN junction at the inclined periphery of thelayered composite 10 is not damaged.

Also, since the cutting position for dividing into devices is away fromthe inclined periphery 10 a of the layered composite 10,short-circuiting at the interface of the PN junction can be prevented,which is caused by chips produced by cutting the metal member 7.

In the nitride semiconductor light-emitting device according toEmbodiment 8 of the present invention, the electrodes are disposed so asto be separated by the layered composite 10. It is therefore unnecessaryto remove the luminescent layer to form one of the electrodes, unlike adevice having the electrodes on one side. Thus, since the luminescentregion can be secured without reducing the area of the luminescentlayer, the luminous efficiency can be increased.

Also, in the nitride semiconductor light-emitting device according toEmbodiment 8 of the present invention, the electrodes are disposed withthe layered composite 10 therebetween. It is therefore easy to applycurrent to the entire luminescent layer uniformly, and thus the entireluminescent layer can uniformly and efficiently emit light.

In particular, if the light-emitting device includes a plurality oflayered portions, it can exhibit superior uniformity in thelight-emitting surface over a relatively large area.

Furthermore, since in the nitride semiconductor light-emitting deviceaccording to Embodiment 8 of the present invention, the transparentelectrode 21 (8) is provided over substantially the entire surface ofthe n-type nitride semiconductor layer, current can be uniformlyinjected to the entire luminescent layer, and thus the entireluminescent layer can uniformly emit light.

However, the invention is not limited to this, and an n-type electrodein a network (grid) may be provided over substantially the entiresurface of the n-type nitride semiconductor layer so that light isemitted through the spaces between the grids, or an n-type electrode maybe provided to part of the n-type nitride semiconductor layer.

Since the n-type semiconductor layer has a lower resistance than thep-type nitride semiconductor layer, current is easily diffused in then-type nitride semiconductor layer. Accordingly, even if a grid n-typeelectrode is used, the grid (the area of regions where the electrode isnot formed) can be increased, so that the electrode does not blockemitted light much. Also, even if an n-type electrode is provided topart of the n-type nitride semiconductor layer, current can be injectedto a luminescent layer having a relatively large area.

Modification Third Aspect, Modification of the Eighth Embodiment

In the above-described Embodiment 8, the n-type nitride semiconductorlayer 2 is etched partway in the thickness direction, so that thelayered composite includes at least part of the n-type semiconductorlayer. However, the invention is not limited to this. Only the p-typenitride semiconductor layer 3 and luminescent layer 4 may be etched todefine a layered portion 810-1, as shown in FIG. 45. Alternatively,after etching the p-type nitride semiconductor layer 3 and theluminescent layer 4, the n-type nitride semiconductor layer 2 iscontinuously etched until the sapphire substrate is exposed so that thelayered portion 810-2 include the p-type nitride semiconductor layer 3,the luminescent layer 4, and the n-type nitride semiconductor layer 2,as shown in FIG. 46.

Embodiment 9 Third Aspect

A nitride semiconductor light-emitting device according to Embodiment 9of the present invention has an arrangement in which four layeredcomposites are arrayed in a line, as shown in FIG. 47.

Specifically, in the nitride semiconductor light-emitting device ofEmbodiment 9, 16 layered portions 810-3 (each composed of a p-typenitride semiconductor layer and a luminescent layer) in frustum oftetragonal pyramid are arrayed in a 4 by 4 matrix on one surface of ann-type nitride semiconductor layer 2, as shown in FIG. 50. Thus, thelight-emitting device has a relatively large area.

The other surface of the n-type nitride semiconductor layer 2 isentirely covered with a transparent electrode 21 (8) shared by all thelayered composites 810. The transparent electrode 21 (8) is used as then-type ohmic electrode, and an n pad electrode 23 is formed in thecenter of the transparent electrode.

The nitride semiconductor light-emitting device of Embodiment 9 is cutout between the layered composites away from the peripheries 10 a of thelayered composites 10 (810) such that 16 layered composites 810 arearrayed in a light-emitting device.

Since the nitride semiconductor light-emitting device according toEmbodiment 9 of the present invention is cut out along positionsseparate from the inclined peripheries 10 a of the layered composites10, the interfaces of the PN junctions at the inclined peripheries 10 aof the layered composites 10 are not damaged, and short-circuiting atthe interfaces of the PN junctions can be prevented, which is caused bychips produced by cutting the metal member 7.

Also, the nitride semiconductor light-emitting device of Embodiment 9can increase the luminous efficiency for the same reason in the nitridesemiconductor light-emitting device of Embodiment 8, and thus the entireluminescent layer can efficiently emit light.

In the nitride semiconductor light-emitting device of Embodiment 9, thelayered composite 810 is defined by the p-type nitride semiconductorlayer 3 and the luminescent layer 4 without the n-type nitridesemiconductor layer 2. However, the invention is not limited to this,and the n-type nitride semiconductor layer 2, the p-type nitridesemiconductor layer 3, and the luminescent layer 4 may define a layeredcomposite 810-4, as shown in FIG. 48.

In the nitride semiconductor light-emitting device of Embodiment 9, then-type nitride semiconductor layer 2 may be formed separately for eachdevice on a wafer instead of being formed separately for each layeredcomposite in one device (FIG. 49). Then, the wafer is divided intodevices in the spaces between the n-type nitride semiconductor layers 2.

The layered composites 810 of the nitride semiconductor light-emittingdevice of Embodiment 9 are formed in frustum of a tetragonal pyramid.However, it is not limited to this, and corn frustum layered composites810-4 may be used (FIG. 51).

(Other Constituents and Structures in the Present Invention)

(Light-Emitting Device 10000)

The constituents in the above-described embodiments (light-emittingdevice 10000) will now be described in detail. The constituents andstructures may be applied in combination to the embodiments.

(Device-Structured Composite 10100)

A device-structured composite 10100 used in the light-emitting device10000 of the present invention may be defined by a layered structureincluding a first conductivity type layer 2, an active layer(luminescent layer 4), and a second conductivity type layer 3 which aredeposited in that order on a substrate 1, as shown in FIGS. 59A and 59B.Alternatively, the first conductive layer 2 and the second conductivitytype layer 3 may be horizontally joined to each other. A combination ofthese structures may also be used. For example, the cross section of thejoined surface may form a polygonal line (continuous line), an inverse Vshape, a V shape, or any other complex shape.

Specifically, the light-emitting device 10000 includes a layeredstructure 10100 as the device-structured composite 10100. Thedevice-structured composite 10100 includes the first conductivity typelayer 2, the luminescent layer (active layer) 3, and a secondconductivity type layer 3 which are deposited in that order on thesubstrate 1, as shown in FIGS. 59A and 59B. In this instance, aluminescent structured portion 5110 includes the first and secondconductivity type layers separated by the luminescent layer, as shown inthe figure. Alternatively, the first and second conductivity type layersmay be horizontally joined to each other, as described above, or theluminescent structured portion may have complex joined surfaces in thevertical and horizontal directions. The light-emitting device may have aMIS structure, a p-n junction structure, a homojunction structure, aheterojunction structure (double heterojunction structure), or a PINstructure, or may be a unipolar device. However, a preferred structureis such that the active layer lies between an n-type layer and a p-typelayer, like, for example, a p-n junction structure in which the firstand second conductivity type layers have different conductivity typesfrom each other.

The semiconductive materials used in the layered structure defining thestructured device body 10000 include InAlGaP, InP, and AlGaAs, mixturesof these materials, and GaN nitride semiconductors. Exemplary GaNnitride semiconductors include GaN, AlN, InN, and their mixed crystals,group III-V nitride semiconductors (In_(α)Al_(β)Ga_(1−α−β)N, 0≦α, 0≦β,α+β≦1). In addition, other mixed crystals may be used in which B is usedas the entire or a part of the group III element, or in which part ofthe N being a group V element is replaced with P, As, or Sb. Thefollowing description uses nitride semiconductors, but other materialsmay be used.

The luminescent layer may comprise an InGaN semiconductor, andwide-bandgap luminescent layers may emit green or blue light in visibleregions, and violet light and shorter-wavelength light in theultraviolet region.

In the embodiments, the first conductivity type layer 2 and the secondconductivity type layer 3 are defined as an n-type layer and a p-typelayer, respectively, and they may be reversed. The semiconductor layeredstructure 10100 may be deposited by MOVPE (metallorganic vapor phaseepitaxy), HVPE (hydride vapor phase epitaxy), MBE (molecular beamepitaxy), or MOCVD (metallorganic chemical vapor deposition).Preferably, MOCVD or MBE is applied.

The substrate used for depositing the semiconductor layered structure10100 of the present invention may be made of a known non-nitridematerial different from nitride semiconductors, capable of growingnitride semiconductors. Such non-nitride substrates include: insulativesubstrates, such as C-plane, R-plane, or A-plane sapphire or spinel(MgAl₂O₄); SiC (including 6H, 4H, 3C); ZnS; ZnO; GaAs; Si; and oxidesubstrates lattice-matching with nitride semiconductors. Preferably,sapphire or spinel is used. Alternatively, nitride semiconductorsubstrates may be used, such as GaN and AlN. For other semiconductors,conventionally known substrates based on the same constituents ornon-nitride substrates, such as Si, may be used.

(Semiconductor Layered Structure 10100)

The semiconductor layered structure 10100 of the light-emitting device10000 is deposited on the substrate 1 with an underlayer 500 or the liketherebetween, as shown in, for example, FIGS. 57A to 57D, 39, 59A, and59B. The underlayer 500 may be included in the structured device body10100 or operational portion, but is generally provided to serve as anon-operational portion only for growing the structured device body. If,in particular, a non-nitride semiconductor substrate is used, alow-temperature deposited buffer layer is used as the underlayer forcrystal-nucleation or nuclear growth. Preferably, Al_(x)Ga_(1-x)N(0≦X≦1) is deposited at a low temperature (200 to 900° C.) and,subsequently, grown at a high temperature to a thickness (singlecrystal, high-temperature deposited layer) of about 50 Å to 0.1 μm. Alayer formed by a deposition known as ELO (Epitaxial Lateral Overgrowth)may be used as the underlayer 500 or in the device layered structure10100, the ELO in which growth portions, such as an island-shapedportions (protrusions, openings in the mask), are deposited prior to theother portions or selectively on a substrate or an underlayer so thatthe portions grow in the horizontal direction to join to each other andthus form a layer. Thus, the resulting structured device body can havecrystallinity, and particularly crystal defects can be reduced.

N-type dopants used in the nitride semiconductors include group IVelements, such as Si, Ge, Sn, S, O, Ti, and Zr; and group VI elements.Among these preferred are Si, Ge, and Sn. More preferably, Si is used.P-type dopants include, but not limited to, Be, Zn, Mn, Cr, Mg, and Ca,and preferably Mg is used. By implanting dopants as an accepter or adonor, nitride semiconductor layers having respective conductivity typesare provided to define respective conductivity type layer describedlater. Nitride semiconductors can be used as the n-type layer even if itis not doped. For other materials, such as AlGaAs, a suitable dopant isused. The first conductivity type layer and the second conductivity typelayer in the present invention may partially include an undoped layer ora semi-insulative layer, or a portion partially parasitic in theconductivity type layers may be formed in an opposite conductivity-typeembedding layer.

First Conductivity Type Layer 2)

Preferably, the first conductivity type layer 2 is doped with anappropriate conductivity type dopant and given a structure capable ofsupplying and diffusing carriers into the surfaces of electrode-formingareas and the active layer, as shown in the structured device body ofthe embodiments. It is particularly preferable that a current-diffusingconductor 8 (contact layer) supplying carriers from the electrodeportion 5200 to the luminescent structured portion 5110 to diffuse thecarriers in planes is doped at a higher concentration. In addition tosuch charge-supply, in-plane diffusion layers (contact layer and itsadjacent layers), an interlayer for transferring or supplying charges tothe luminescent layer in the layering direction, or a cladding layer forconfining second conductivity type carriers in the luminescent layer maybe provided, preferably. In a nitride semiconductor device, theinterlayer disposed between the luminescent layer 4 and the contactlayer of the in-plane diffusion layers (regions) preferably comprises alightly doped layer (undoped layer) which is undoped or doped at a lowerconcentration than the in-plane diffusion layers (regions), and/or amultilayer film. This is because the lightly doped layer can recovercrystallinity degraded by the heavily doped layers (in-plane diffusionlayers) so that the crystallinity of the cladding layer and luminescentlayer provided over the in-plane diffusion layers, and because thearrangement of adjoining the heavily doped layer and the lightly dopedlayer can promote in-plane diffusion and increases the pressureresistance. The multilayer film preferably has a periodic structurecomposed of at least two types of layers alternately deposited.Specifically, the periodic structure includes a nitride semiconductorlayer containing In and a layer having a different composition from thatof the nitride semiconductor layer, preferablyIn_(x)Ga_(1-x)N/In_(y)Ga_(1-y)N (0≦x<y<1). In particular, use of aIn-containing nitride semiconductor layer, preferably use of pluralityof it as a well layer, increases the crystallinity of the luminescentlayer. Alternatives to the multilayer film having a periodic structureincluding layers having different compositions may be a structureincluding layers whose compositions are gradually varied, whose dopantconcentrations are varied, or whose thicknesses are varied. Preferably,a structure constituted of layers with thicknesses of 20 nm or less,more preferably 10 nm or less, deposited on top of one another is usedfrom the viewpoint of increase of the crystallinity.

(Luminescent Layer [Active Layer] 13)

The structured device body 10100 of the present invention preferablyincludes the luminescent layer emitting light between the first andsecond conductivity type layers. More preferably, the luminescent layercomprises an In-containing nitride semiconductor from the viewpoint ofobtaining an appropriate luminous efficiency in the range of UV tovisible light (red light). In particular, the use of an InGaN layerallows the In ratio in the mixed crystal to be varied so as to providelight having a desired wavelength. Alternatively, GaN, AlGaN, and othernitride semiconductors having a higher bandgap than the InGaN may beused for a luminescent layer for emitting UV light.

Still more preferably, the luminescent layer is of an active layerhaving a quantum well structure, which may be a single-quantum wellstructure with a single well layer, or more preferably a multi-quantumwell structure including a plurality of well layers deposited on top ofone another, separated by barrier layers. The well layer preferablycomprises InGaN, as in the above described luminescent layer. Thebarrier layers preferably have larger bandgap energy than the welllayer. For example, InGaN or AlGaN is used. The thicknesses of the welllayer and the barrier layer are preferably 30 nm or less, and morepreferably 20 nm or less. Still more preferably, the well layer is 10 nmor less. Thus, the resulting luminescent layer can exhibit a highquantum efficiency. The well layer and the barrier layer may be dopedaccording to the conductivity type. The number of the barrier layerbetween a pair of the well layers may be one or more.

(Second Conductivity Type Layer 3)

The second conductivity type layer 3 preferably includes a claddinglayer for confining carriers in the luminescent layer, and a contactlayer on which an electrode is formed. Preferably, these two layers areseparate from each other, and the contact layer is more distant from theluminescent layer than the cladding layer and is heavily doped at a highconcentration. In the nitride semiconductor, the cladding layerpreferably comprises a nitride semiconductor containing Al, and morepreferably an AlGaN layer. More preferably, the cladding layer isprovided close to the luminescent layer, and still more preferablyadjoining the luminescent layer. Thus, the luminous efficiency of theluminescent layer can be enhanced. Preferably, a layer is providedbetween the contact layer and the cladding layer at a lowerconcentration than these two layers, so that the resulting device canexhibit high pressure resistance. The contact layer may be doped at ahigh concentration, thereby enhancing the crystallinity advantageously.Since the contact layer is provided in the luminescent portion 5110inside the electrode-forming surface, as shown in FIG. 58, it can serveto diffuse carriers. In the present invention, however, an upperelectrode 2200 extending on a part of the electrode-forming surface anda lower electrode 2100 having a larger area, or a wider section, thanthat of the upper electrode are provided to allow them to serve as acurrent diffusion layer and a diffusion conductor, thus helping thediffusion of p-type carriers, which transfers through a nitridesemiconductor at a low speed. Also, the contact layer is preferablyformed to a smaller thickness than the thicknesses of the other layers(cladding layer, interlayer) and doped at a higher concentration thanthe other layers to be a high carrier-concentration layer. Thus,carriers can be well injected from the electrode.

(Current-Diffusing Conductors 8, 9)

In the layered structure 1000100 of the present invention, thecurrent-diffusion conductor 8 may be provided inside the structureddevice body (in the first conductivity type layer 8) or on (theelectrode 2100 on) the structured device body. Specifically, as shown inFIG. 58, a first electrode 1000 is provided for the first conductivitytype layer 2 on the exposed electrode-forming surface 5200, and servesas a diffusing conductor 8 for diffusing current in the lateraldirection in the first conductivity type layer 2; an electrode 2100 forohmic contact, electrically coupled with the connecting electrodes(wiring electrodes and wires) is provided for the second conductivitytype layer 3, and serves as a diffusion conductor for widely diffusecurrent in the plane through the partially provided wiring electrode. Adiffusion layer may be provided in the second conductivity type layer 3,or an external diffusing conductor (electrode) may be provided on thefirst conductivity type layer.

(In-Plane Structure of Light-Emitting Device)

The light-emitting device of the present invention includes thestructured portion 5700 including the luminescent structured portion5110 and the electrode portion 5200. The structured portion 5700 of thedevice is formed on the current-diffusing conductor 8 (firstconductivity type layer 2). A single structured portion 5700 may have aluminescent structured portion 5110 (FIGS. 1 to 10, 34, 45, and 46), orhave a plurality of the luminescent structured portions 5110 in acluster. In other wards, a single device structure 5700 includes atleast one pair of the luminescent structured portion 5110 and theelectrode portion 5200. A plurality of the structured portions 5700 ofthe device may be integrated to define an integrated light-emittingdevice 10000.

For wiring the electrodes, each electrode preferably has an ohmiccontact portion where an ohmic contact is established to supply currentin the structure portion of the device. Preferably the electrodes(wiring electrode and pads) are formed corresponding to the ohmiccontact portions. Alternatively, the wiring electrode may be provided sothat separated ohmic contact portions electrically conduct to oneanother. The wiring electrode 1120 or 766 may be provided to adevice-mounting base, as described later.

The electrodes of the structured device body are provided on theelectrode-forming surfaces of the conductivity type layers, depending onthe shape or form of the structured device body. Accordingly, the secondconductivity type layer and the first conductivity type layer partiallyexposed by removing part of the luminescent layer are used as theelectrode-forming surfaces, so that the second electrode and the firstelectrode can be respectively provided above and below the luminescentlayer, over the substrate. Alternatively, both electrodes may be formedon the same side. In such a case, the electrode-forming surfaces aredisposed in a different manner.

(First Electrode 1000)

The first electrode 1000 is formed on at least part of the exposed area2 s of the first conductivity type layer 2 being the electrode-formingregion 5200. In the form according to the second aspect, the firstelectrode is disposed separately from the luminescent structured portion5110 in the plane, and serves to inject current into the firstconductivity type layer 2 for establishing an ohmic contact. The exposedarea 2 a of the first conductivity type layer 2 may be provided in theouter region of the structured portion 10100 of the device so as tosurround the luminescent structured portion 5110, as shown in thefigure. Alternatively, as shown in FIG. 58, the substrate 1 may beexposed at the outer region (exposed region 4 s) of the device and theperiphery 6110 a of the first conductivity type layer 2 may be inclinedto serve as a light-reflection portion or a light-extraction portion. Inthis instance, by setting the angles of the electrode-forming surface atthe inclined periphery with respect to the normal of the surface of thesubstrate to be larger than the angle of the periphery 5110 a of theluminescent structured portion 5110, light propagating in the lateraldirection in the first conductivity type layer 2 can efficiently beextracted advantageously. The exposed area 2 s may be provided to theluminescent structured portion 5110 in the operational portion 57 of thedevice in such a manner as to be exposed at the first electrode 1000(5110 a), thus functioning as a light-extraction groove. In addition, aprotrusion may be provided as a nonluminescent structured portion intowhich current is not injected (for example, electrode portion 5200 ornon-operational portion 5800 of the device) in the area exposed at theelectrode 1000. The protrusion can contribute to reflection or lightextraction.

The first electrode 1000 functions to diffuse and inject current intothe luminescent structured portion 5110. By adjusting the in-planediffusion in the in-plane diffusing layers (8 and 9) of the firstconductivity type layer 2, the second conductivity type layer 3, and thesecond electrode 2000 (lower electrode layer 2100), more specifically,by appropriately adjusting sheet resistances to control the intervalbetween the first electrode and the second electrode, a desired width isgiven to the luminescent structured portion 5110 and a desired state inin-plane diffusion can be achieved.

The first electrode 1000 includes a pad portion 1100 and a connectingelectrode portion 1200. These portions may be formed in the sameelectrode structure, or may have different structures such that theelectrode 1000 is defined by an electrode for establishing an ohmiccontact and a pad electrode is formed only in the pad portion 1100.

(Second Electrode 2000)

The lower electrode 2100 is formed over substantially the entire surfaceof the exposed area 2 s of the second conductivity type layer 3 in theluminescent structured portion 5110, as described above, thusfunctioning as a diffusion layer for diffusing current in the plane inthe luminescent structure portion 5110. If the second conductivity typelayer 3 has a current diffusion layer inside, the in-plane diffusingelectrode 2100 is not necessary. However, both the current diffusionlayer in the structured portion and the current diffusion electrode maybe provided because the device structure often makes it difficult todiffuse current. In use of nitride semiconductors, in-plane diffusion inthe p-type layer often becomes insufficient. It is therefore preferablethat second electrode 2000 include a pad portion 2200 p for externalconnection, an upper electrode 2200 extending from the pad electrode todiffuse current to the luminescent structured portion 5110, a wiringelectrode 2200 a (2200 b), and a lower electrode 2100 having a largerarea than that of the wiring electrode 2200 a (2200 b) to expand thesecond electrode 2000 in the plane.

The lower electrode 2100 is preferably light transmissive, as describedabove. If light is extracted through the substrate 1, as shown in FIGS.16B, 33B, 54A, and 55, a reflection layer may be provided on thelight-transmissive electrode or a light-transmissive insulating layer onthe light-transmissive electrode, or an electrode structure or areflective electrode may be provided which includes a reflectiveelectrode layer overlying a light-transmissive electrode layer. Ineither case where light is extracted through the substrate 1 or thesecond conductivity type layer, it is preferable that the lowerelectrode layer 2100 of the second electrode 2000 is provided withopenings to be light transmissive, or that the lower electrode layerproper 2100 a is light transmissive, as well.

The first and second electrodes 1000 and 2000, particularly the lowerelectrode 2100 of the p-type nitride semiconductor layer, are formed ofa metal, an alloy or an composite containing at least one selected fromthe group consisting of nickel (Ni), platinum (Pt), palladium (Pd),rhodium (Rh), ruthenium (Ru), osmium (Os), iridium (Ir), titanium (Ti),zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta),cobalt (CO), iron (Fe), manganese (Mn), molybdenum (MO), chromium (Cr),tungsten (W), lanthanum (La), copper (Cu), silver (Ag), and yttrium (Y).Compounds containing at least one of these metals may be used, such asconductive oxides and nitrides. Among these, preferred are conductivemetal oxides (oxide semiconductors), such as indium oxide doped with tin(Indium Tin Oxide, ITO) of 50 Å to 10 μm in thickness, ZnO, In₂O₃, andSnO₂ because of their light transmittancy. Such an oxide semiconductorfunctions intermediately between the conductivity type layers 2 and 3and their respective electrodes 1000 and 2000, and the conductivity ofthe conductivity type layers 2 and 3 may be set to be the same as thatof the metal oxide. If oxide semiconductor layers having differentconductivity types are used as the electrodes, an interlayer (oppositeconductivity type layer, oxide semiconductor, metal layer) may bedisposed between the electrode and the device-structured composite10100. Since the oxide semiconductor or electrode material can serve asthe diffusing conductor 2100 (9), the diffusion conductor 8 on the firstconductivity type layer 2 side may be constituted of such asemiconductor layer. If the lower electrode 2100 is of a metal layer,the lower electrode can be formed to such a small thickness as to ensuretransmittance; if the lower electrode layer 2100 having an openings 2100b, a reflective metal, such as Al, Ag, or Rh, may be used for the lowerelectrode 2100.

FIGS. 60A to 60E show exemplary forms of the second electrode 2000including the lower electrode 2100 and the upper electrode 2200 (wiringportion 2200 a). In the second electrode, pad portions 2200 p may bearranged in a line 2200 a (designated by dotted lines) to serve as theconnecting electrode portion 2200 a (FIG. 58); the lower electrode 2100may be defined by the lower electrode proper 2100 a having openings 2100b formed corresponding to openings 600 of the structured portion 10100of the device (FIG. 60B); the lower electrode 2100 may partially have anopening 2100 b, and an electrode 2200 a serving as the wiring portion2200 a (pad portion 2200 p) is formed on the surface of the lowerelectrode 2100, across the opening 2100 b (surface of the secondconductivity type layer 3), as shown in FIG. 60D. A compound electrode,such as an oxide electrode, can enhance the adhesion in the secondelectrode. The second electrode 2200 a filling the opening 2100 b may besuch that the second electrode 2000 is defined by electrodes 2200α(upper electrode pad portions 2200 p-1, 2200 p-2) disposed on theelectrode 2100, across the opening 2100 b of the lower electrodetogether with recesses 600 formed in the second conductivity type layer3.

Since the electrode 2100 of the second electrode is formed in theluminescent structured portion 5110, it is necessary to be transmissiveor reflective so that light can be extracted or reflected effectively.It is therefore advantageous for either light-extraction direction thatthe electrode has a portion (electrode proper 2100 a) with a highlight-transmissive property (light transmittance) (formed of a materialhaving a low light absorption), or that the light transmittance (orabsorption) of the electrode, the area ratio of the openings 2100 bdetermining the transmittance (total area of the openings/area of theelectrode proper [5300]), and/or the proportion and distribution of theopenings are adjusted.

The surface 2 s of the electrode from which light is extracted may beformed into an irregular portion 600, as shown in FIG. 60A; recesses 600a may be formed in the second conductivity type layer 3, correspondingto the openings 2000 b in the electrode 2300 so that irregularities 600are defined by the interface of different types of material: the uppersurfaces 600 c (interface with the electrode material) of protrusionsand the lower surface 600 a (interface with the protective film orinsulating material) of recesses, as shown in FIGS. 60C and 60E. Thesestructures contribute to favorable light extraction or reflection. Also,by setting the angle of the sidewall 600 b large, reflection at thesidewall is increased to enhance the light-extraction efficiency. Theirregularities 600 may be provided at an end, a side surface, an exposedsurface, or an interface (between layers, between a layer and thesubstrate, between a layer and a metal, between a layer and a film, suchas an insulating layer) of the structured portion 10100 of the device.For example, as shown in FIG. 57, in order to increase thelight-extraction efficiency by diffusing light propagating in thedirection designated by the arrow and controlling the direction of thelight, the irregularities 600 are formed in the substrate 1, and thedevice-structured composite 10100 is deposited to the irregularities sothat an irregular interface is formed between the substrate 1 and thesemiconductor of the unit. The irregular interface 600 may be formed atthe surface of the underlayer 500 exposed by removing the substrate 1 ina removal region 700. By forming the irregular interface 600, thelight-extraction efficiency and power of the light-emitting device areenhanced advantageously.

The irregularities 600 and the openings 2100 b (electrode proper 2000 a)of the lower electrode 2100 of the periodic structure are formed in apattern of protrusions (upper surfaces) and openings 2000 b or a patternof recesses (bottom surfaces) and electrode proper 2100 a in a dotmanner, a grid, a honeycomb, a branch pattern, a rectangular shape, apolygonal shape, a circular shape, or any other shape. The size of theirregularities is set at λ/(4n) or more (n represents the refractiveindex of the material forming the irregularities; λ represents theemission wavelength of the luminescent layer) so as to reflect, diffuse,or extract light. More specifically, the intervals of the openings,protrusions or recesses, the length of sides (rectangular or polygonalshape), or the diameter (dot manner, circular shape) is set at 1 to 10μm, and preferably 2 to 5 μm. The shape in sectional view is notparticularly limited, and the side surface of the recesses may besubstantially vertical or inclined (in a mesa manner or reversed mesamanner). The reflection layer in the present invention is formed at theend surface, exposed surface, or interface with the substrate of adevice to which reflection functions are given, so that desired lightextraction (for example, at the substrate 1 side) is achieved.Specifically, the reflection layer may be provided, as in theirregularities 600, on the exposed surfaces 1 s (5200) and 2 s (5300) ofthe first and second conductivity type layers, the openings 200 b of theelectrode, and the periphery 5110 a of the semiconductor layers (firstand second conductivity type layers, luminescent layer 5110), andfurther on a surface of the substrate. The periphery may be inclined toreflect light in a desired direction. A metal layer (for example, anelectrode) may be given reflectivity, and further, the reflection layermay be formed on the surfaces 600 a to 600 c of the irregularities 600.The reflection layer may comprise a metal film, oxide film (insulatingfilm), multilayer reflection film (DBR), or the like. For visible light,particularly from a luminescent layer formed of In_(x)Ga_(1-x)N (0≦x≦1),Al or Ag is used as a high reflection layer. A suitable material isselected according to the position and material of the layer-formingregion (end of the device), emission wavelength, or and the like.

The first electrode 1000 and the second electrode 2000 or the firstelectrode 1000, the second electrode 2000 and the upper electrode 2200(pad portion 2200 p, connecting electrode) may be formed of the samematerial in the same structure at one time. For example, theseelectrodes each comprise a multilayer film, such as Ti/Au or Ti/Al,including a Ti layer (first layer) for establishing an ohmic contactwith the first conductivity type layer and enhancing adhesion and a padlayer (second layer) of gold, Al, or a platinum metal in that order fromthe exposed area 2 s side. A high-melting-point metal layer (W, Mo, aplatinum metal) may be provided as a barrier layer between a first layerfor ohmic contact (W, Mo, or Ti is suitable for establishing an ohmiccontact with the first conductivity type layer) and a second layer orpad layer. Preferred structures include, for example, W/Pt/Au and Ti/Rh(second layer a)/Pt (second layer b)/Au, and these are particularlysuitable for the first electrode (for ohmic contact). It is particularlypreferable that Rh, which has high reflectivity and barrier properties,is used as the second layer from the viewpoint of enhancing the lightextraction efficiency. The electrode 2300 for establishing an ohmiccontact with the second conductivity type layer 3 preferably comprisesNi/Au or Co/Au, in that order from the exposed area 2 s side, or aconductive oxide, such as ITO, or platinum metals, such as Rh/In orPt/Pd.

Among these, preferred material for the lower electrode 2100 (electrodeproper 2100 a) is Ni/Au (light-transmissive electrode material) or Rh/Ir(reflective electrode material).

Fourth Aspect

According to a fourth aspect of the present invention, a light-emittingapparatus is provided which includes the light-emitting device accordingto the first to third embodiments. In particular, the light-emittingapparatus uses a light-transforming member for a filler or a lens totransform at least part of the light emitted from the light-emittingdevice.

Embodiment 10

Embodiment 10 describes a device composite 10300 in which any one of thelight-emitting devices 10000 of Embodiments 1 to 9 according to thefirst to third aspects of the present invention is mounted and bondedonto a multilayer board 10400 with the electrode surfaces of the devicetherebetween. FIG. 54A shows a schematic sectional view of the devicecomposite. In another form, the light-emitting devices 10000 may definethe device composite 10300, and are mounted and bonded such that, asshown in FIG. 54A, the first electrodes 21 (pad portions 29) (theelectrode and pad portion of the first conductivity type layer 2)separately provided in the device, as described above, are connected toeach other with an electrode 11200 of the board 10400 and the separatelyprovided second electrodes 31 (pad portions 32) (the electrode and padportion of the second conductivity type layer 3) are also connected toeach other on the board 10400 side. The electrodes 11200 of the board10400 are isolated by an insulating film 11100 or the like correspondingto the electrodes 21 (29) and 31 (32) on the light-emitting device side,and additional electrodes 11300 are provided for external connection.The board may include a device portion 11500. In the present embodiment,the device portion includes a p-type layer (first conductivity typelayer) 11500 a and n-type layer (second conductivity type layer) 11500 bas a current-shielding and static-shielding device (device-structuredportion 11500). While, in the present embodiment, a single deviceportion 11500 is provided in the board 10400, two or more deviceportions may be provided and connected with electrodes of externaldevice 10000 or mounting base 20100. The shielding device may beincorporated in the light-emitting apparatus 20000 (mounted portion22200) on the board 10400 and connected to the light-emitting devicewith wire.

The electrodes 21 and 31 of the light-emitting device 10000 and theelectrode 11200 of the board 10400 are connected to each other with ajunction layer 11400. Alternatively, part of the electrode of the device10000 or part of the electrode 11200 of the board 10400 may be includedin the junction layer. For example, the junction layer may bealternative to the pad portions 11 and 22 p.

The board 10400 may be of a normal submount, having no device-structureportion 11500. The board 10400 may be connected to the outside withconnecting electrodes 11300 by wiring, or an electrode for thedevice-structured portion of the board or an electrode layerelectrically connecting the interior to the exterior may be formed onthe mounting side to be used as the electrodes 11300 and the junctionlayer 11400.

(Support 900)

A support 900 may be prepared by removing the substrate 1 used fordepositing the device layered structure 10100 of the light-emittingdevice structure 10000. For example, as shown in FIG. 59B, the removalportion 700 to be removed may be defined by the substrate 400, thesubstrate 400 and a part or the entirety of an interlayer 500 betweenthe substrate and the layered structure 10100, or part of the firstconductivity type layer 1 in addition to these layers. In other words,any unnecessary region can be removed except the device layeredstructure 10100. Specifically, the removal portion 700 is separated fromthe device layered structure 10100 bonded and mounted on a multilayerboard, such as a submount, as shown in FIG. 16B or bonded to the support1700 as shown in FIGS. 59A and 59B, by grinding, deliquescence or fusionof part of the layered portion on the substrate 1 through a chemicalprocess (with an etchant), or decomposition by laser exposure (laserablation). A stress or strain may be placed between the substrate 1 andthe device layered structure 10100 to break layers by applyingmechanical grinding or external force. These methods may be combined toremove the removal portion 700.

Preferably, the removal portion, such as the substrate 1, is removed bytransfer in which the device layered structure is bonded to the support900 with a junction layer 800 therebetween. In this instance, thesupport 700 is made of a suitable material according to purpose. Inorder to enhance the heat radiation of the device, AlN, BN, SiC, GaAs,Si, or C (diamond) is preferably used as a heat-radiating support. Othermaterials for the support include semiconductor substrate constituted ofsemiconductors, such as Si, SiC, GaAs, GaP, InP, ZnSe, ZnS and ZnO,elemental metal substrates, and complex substrates constituted of atleast two metals not dissolving with each other or having low solubilitylimits. Such a metal material is, for example, composed of at least onemetal selected from high-conductivity metals, such as Ag, Cu, Au and Pt,and at least one metal selected from high-hardness metals, such as W,Mo, Cr, and Ni. Preferably, the metal support is a Cu—W or Cu—Mocomplex. The material and the bonding method of the support 900 areselected in view of the adsorption and loss by the support of lightemitted from the light-emitting decide, the adhesion to thedevice-structured composite 10100 (the difference in thermal expansioncoefficient between the device-structured composite 10100 and thesupport 900 or the mounting material 20300), or other factors. If lightis extracted through the support 900, a light-transmissive material isselected, and is bonded with a light-transmissive adhesion layer 800,such as of silver paste, or by a method using no adhesion layer so thatlight loss is reduced. If light is extracted from the removal portion700 side, a reflection layer of Al, Ag or the like is preferablyprovided to the adhesion layer 800, the support 900, or part of thelayered structure 10100 to enhance the extraction efficiency. It goeswithout saying that if the order of deposited semiconductor layers isreversed by transfer, the first conductivity type layer 2 and the secondconductivity type layer 3 in the device structure are interchanged, asdesignated by the double-headed arrow shown in FIG. 59B.

(Junction Layer 800, Junction Layer 11400, Adhesion Member 20400)

For adhesion between the support 900 and the device-structured composite10100; adhesion between the device-structured composite 10100 (10000)and the multilayer board 10300; and adhesion or junction between thelight-emitting device 10000, the support 900, or the multilayer board10300 and the mounting base 20100 (housing 20200), a junction layer 800(11400) or an adhesion member 20400 may be used. For forming them, amixed or complex composition (organic) or a solder, such as Ag paste,carbon paste, or ITO paste is used. In view of the heat radiation fromthe light-emitting device 10000, heat-resistant material, such as Au,Sn, Pd, and In, is effective for large-area, high-current-driven, highlyexothermic devices. These metals may be formed in a single layer, acomposite, or an alloy. Preferred combinations of a first and a secondeutectic-forming layer include Au—Sn, Sn—Pd, and In—Pd. More preferably,the first eutectic-forming layer is formed of Sn and the secondeutectic-forming layer is formed of Au. A metal bump or a metal-metaljunction, such as a Au—Au junction, may be used.

Such a junction layer may be formed on an underlayer, such as anadhesive metallizing layer, provided over the base (substrate 400,surface of the device-structured composite 10100, support 900, mountingbase 20100, or multilayer board 10100), or on a reflection layer forreflecting light from the light-emitting device, thus forming anadhesion layer (junction layer) of a eutectic, a multilayer eutectic, analloy, or the like. An antioxidant surface protection layer may beprovided on the surface of the junction layer. In addition, an adhesivemetallizing layer (adhesive layer), a surface protection layer, and anadhesion layer (junction layer) may be provided on the mounting sidewhere an adhesion is established, and these layers on both sides may bebonded and joined.

For example, the junction layer 20400 is disposed between the substrate(sapphire) 10 of the light-emitting device 10000 and the mounting region20200 (whose surface is coated with, for example, Ag), as shown in FIG.56. The junction layer 20400 is formed by depositing Al (0.2 μm,reflection layer)/W (0.2 μm)/Pt (0.2 μm), seven pairs of Au (0.3 μm)/Sn(0.2 μm), and a Au (10 nm) layer, in that order, from the substrateside, by depositing a Au layer on the mounting region 20200, and byheating and compressing the layers to bond the light-emitting devicewith the adhesion layer 20400. As for the junction layer 800 for bondingthe device-structured composite 10100 to the support 1700, for example,a Ni—Pt—Au—Sn—Au multilayer film is deposited on the p electrode of thesecond conductivity type layer (p type layer) at respective thicknessesof 0.2, 0.3, 0.3, 3.0, and 0.1 μm, and a Ti adhesion layer, a Pt barrierlayer, and a Au second eutectic-forming layer are deposited in thatorder at respective thicknesses of 0.2, 0.3, and 1.2 μm on the surfaceof a 200 μm thick metal substrate 1700 made of a complex of 30% of Cuand 70% of W. These layers are heat-compressed.

(Device Composite 10300)

For installing the light-emitting device into the light-emittingapparatus 20000, the light-emitting device 10000 may be mounted on themultilayer board 10400, such as a heat sink or a submount, to prepare adevice composite 10300 which is a mounting composite including thedevice, as shown in FIGS. 16B, 33B, 54A, and 55. In this instance, thematerial of the board 10400 on which the light-emitting device 10000 ismounted is selected, as well as the above-described support, accordingto purpose. For example, it is selected in view of heat radiationproperties or the light-extraction structure. The device composite 10300is bonded to the mounting region 20200 of the light-emitting apparatus20000, at the surface opposing the surface joining to the light-emittingdevice 10000.

If the multilayer board 10400 in the present invention is bondedopposing the electrodes of the light-emitting device 10000, electrodestructures 11200 a and 11200 b or 766 are provided to the board 10400corresponding to the electrodes 21 (29) and 31 (32) of thelight-emitting device 10000. If the board 10400 is bonded opposing theopposite side (substrate 400) to the electrodes of the light-emittingdevice 10000, an adhesion layer or the like for bonding is providedinstead of the electrodes, but another type of electrode may be providedfor connecting the board to the light-emitting device 10000 by wiring.The electrodes 11200 of the board 10400 may be provided only on thesurface bonding to the light-emitting device 10000, as shown in thefigures. Alternatively, the electrodes may be provided, as amounting-surface electrodes 11400, on the mounting surface opposing thebonding surface of the board 10400 such as to extend from the bondingsurface to the mounting surface, to lie on the bonding surface, or to becommunicated or electrically coupled from the bonding surface of thelight-emitting device to the mounting surface through a through hole orvia hole.

Although the figures shows an example in which a single light-emittingdevice 10100 is mounted on a single multilayer board 10400, a pluralityof light emitting devices 10100 may be integrated and connected to theboard 10400 in parallel, series or their combination with wiringelectrodes of the board 10400 to define the composite 10300 includingthe mounted device. A single light-emitting device 10100 may be mountedon a plurality of multilayer boards 10400, another type of boardcomprising a differently functioning device, or their combination.Either a plurality of light-emitting devices 10100 or layered boards(devices) 10300 may be arranged in the vertical direction to define adevice composite 10300.

The light-emitting device 10000 may be covered, as shown in FIG. 55,with a coating 10500 formed of a light-transmissive inorganic compound,such as SiO₂, Al₂O₃, or MSiO₃ (M represents, for example, Zn, Ca, Mg,Ba, Sr, Zr, Y, Sn, or Pb). The coating 10500 may contain a phosphor(light-transforming member 10600). The light-transmissive material helpsphosphor molecules combine to each other, so that the phosphor depositsto form a layer and adheres on the LED 10000 or the support 10400. Thecoating serves as an insulating protection layer coating the devicestructure 10000. Alternatively, a reflection layer (reflective metallayer, such as Al or Ag layer) may be provided as the coating. A DBR maybe used as the reflection layer.

(Light-Transforming Member 10600, Light-Transforming Layer 23100)

A Light-Transforming Member 10600 And A Light-Transforming Layer 23100in the light-emitting apparatus 20000 absorb part of the light from thelight-emitting device 10000 and emit light having a differentwavelength. A material containing a phosphor may be used as thelight-transforming member or layer. The light-emitting transformingmember 10600 and the light-transforming layer 23100 may be formed as thecoating 10500 by coating the entirety or a part of the light-emittingdevice 100000, or by coating part of the multilayer board 10400 togetherwith the light-emitting device. In the above-described first to thirdaspect, the light-transmissive member or layer may be formed not only inthe light-transmissive protection layer coating the structured compositeor the like, but also in an optical path running from the light-emittingdevice, for example, in a light-transmissive member (lens 24000 orfiller). Binders of the phosphor include: oxides and hydroxidecontaining at least one element selected from the group consisting ofSi, Al, Ga, Ti, Ge, P, B, Zr, Y, Sn, Pb, and alkaline-earth metals; andorganic metal compounds (preferably containing oxygen) containing atleast one element selected from the group consisting of Si, Al, Ga, Ti,Ge, P, B, Zr, Y, Sn, Pb, and alkaline-earth metals. The organic metalcompounds include compounds having an alkyl group or an aryl group, suchas metal alkoxides, metal diketonates, metal diketonate complexes, andmetal carboxylates.

The light-transforming member or layer may be formed as part of asealing member 23000 (24000) of the light-emitting apparatus 20000, orformed as an additional layer 23100 on a sealing member 23000 a orbetween the sealing member 23000 a and a sealing member 23000 b,separate from the light-emitting device 10000, as shown in FIG. 56. Thelight-transforming member may be dispersed in the sealing member 23000,or the light-transforming layer 23100 may serve as the sealing member23000. Also, the light-transforming member or layer may be formed in alayer sedimented in a apparatus base 22000, the mounting base 20100, orthe housing recess 20200.

The phosphor used in the light-transforming member of the presentinvention transforms visible or ultraviolet light emitted from thelight-emitting device into light having a different wavelength, and isexcited by the light from the semiconductor luminescent layer of thedevice-structured composite 10100 to emit light. The phosphor may beexcited by ultraviolet light or visible light to emit light having apredetermined color.

Exemplary phosphors include cadmium zinc sulfide activated by copper andyttrium aluminum garnet phosphors (hereinafter referred to as YAGphosphors) activated by cerium. For long-time use at a high luminance,(Re_(1-x)Sm_(x))₃(Al_(1-y)Ga_(y))₅O₁₂:Ce (0≦x<1, 0≦y≦1, Re is at leastone element selected from the group consisting of Y, Gd, and La) isparticularly preferable. This phosphor is resistant to heat, light andwater because of the garnet structure, and its excitation spectrum canhave a peak at about 470 nm. Also, the peak luminescence can be observedat about 530 nm, and the luminescence spectrum can be so broad as toextend to 720 nm. In the present invention, the phosphor may be amixture of at least two types of phosphor. For example, at least two(Re_(1-x)Sm_(x))₃(Al_(1-y)Ga_(y))₅O₁₂:Ce phosphors having differentproportions of Al, Ga, Y, La, Gd, and Sm are compounded to increase thenumber of RGB wavelength components. For somesemiconductor-light-emitting devices exhibiting variation in emissionwavelength, at least two types of phosphor may be compounded to obtaindesired white-mixed light. Specifically, by compounding phosphors havingdifferent chromaticities, with their amount adjusted according theemission wavelength of the light-emitting device, light can be emittedat a desired point in a chromaticity diagram defined by thechromaticities of the phosphors and light-emitting device. Al least twotypes of phosphor may be contained in a single coating 10500,light-transforming layer 22100, or light transforming member 10600, or asingle phosphor or at least two types of phosphor may be contained ineach layer of a double-layer coating. Thus, colors of light emitted fromdifferent types of phosphor are mixed to produce white light. In thisinstance, in order to sufficiently mix colors of light from phosphorsand to reduce nonuniform browning, it is preferable that the averagegrain sizes and shaped of the phosphors are similar. An aluminum garnetphosphor, which is represented by YAG phosphors, may be combined with aphosphor capable of emitting red light, particularly a nitride phosphor.The YAG phosphor and the nitride phosphor may be mixed in a single-layercoating, or may be separately contained in respective layers of amultilayer coating. The phosphors will now be described in detail.

The aluminum garnet phosphor used in the present invention contains Al;at least one element selected from the group consisting of Y, Lu, Sc,La, Gd, Tb, Eu, and Sm; and one of Ga and In, and is activated by atleast one element selected from the rare earth elements. This phosphoris excited by visible light or ultraviolet light emitted from an LEDchip 10100 to emit light. Such phosphors includeTb_(2.95)Ce_(0.05)Al₅O₁₂, Y_(2.90)Ce_(0.05)Tb_(0.05)Al₅O₁₂,Y_(2.94)Ce_(0.05)Pr_(0.01)Al₅O₁₂, and Y_(2.90)Ce_(0.05)Pr_(0.05)Al₅O₁₂in addition to the above-cited YAG phosphors. Among these used in thepresent embodiment are at least two yttrium aluminum oxide phosphorshaving different compositions, containing Y, and activated by Ce or Pr.

By emitting on a display light generated by mixing blue light emittedfrom a light-emitting device including a luminescent layer made of anitride compound semiconductor with green and red light emitted from aphosphor having a yellow body color for absorbing the blue light, orwith yellow light tinged with green and red, a desired white luminescentcolor can appear on a display. In order to produce such a color mixturein the light-emitting apparatus, the powder or bulk of the phosphor maybe contained in a resin, such as epoxy, acrylic, or silicone resin, orin a light-transmissive inorganic material, such as silicon oxide oraluminum oxide. The material containing the phosphor is formed to such athickness as to transmit light from the LED chip in various shapes, suchas dots or a film, according to how the phosphor is used. By adjustingthe ratio of the phosphor to the light-transmissive inorganic material,the amount of phosphor application, or the phosphor content, andappropriately selecting emission wavelength, a desired color of light,including white can be produced.

Also, by arranging at least two types of phosphor separately forincident light from the light-emitting device, the resultinglight-emitting apparatus can efficiently emit light. For example, alight-emitting device including a reflection member is provided thereonwith a color-transforming member containing a phosphor absorbinglong-wavelength light and emitting long-wavelength light and anothercolor-transforming member containing a phosphor absorbinglonger-wavelength light and emitting longer-wavelength light are layeredone on top of the other, so that reflected light can be usedeffectively. Also, the peak luminescence λp is observed at about 510 nm,and the luminescence spectrum is so broad as to extend to about 700 nm.YAG phosphors capable of emitting red light, which are included inyttrium aluminum oxide phosphors activated by cerium, are also resistantto heat, light and water because of the garnet structure, and exhibitsexcitation and absorption spectra with a peak wavelength in the range ofabout 420 to 470 nm. Also, the peak luminescence λp is observed at about600 nm, and the luminescence spectrum is so broad as to extend to about750 nm.

By substituting Ga for part of the Al in an YAG phosphor having thegarnet structure, the emission spectrum is shifted to the shorterwavelength side; by substituting Gd and/or La for part of the Y in thecomposition, the emission spectrum is shifted to the longer wavelengthside. Thus, emission color can be continuously adjusted by changing thecomposition. For example, the intensity in the long wavelength regioncan be continuously changed depending on the Gd content. Thus, the YAGphosphor provides ideal conditions for transforming blue light emittedfrom nitride semiconductors into white light.

(Nitride Phosphor)

In the present invention, nitride phosphors may be used which contain N;at least one element selected from the group consisting of Be, Mg, Ca,Sr, Ba, and Zn; and at least one element selected from the groupconsisting of C, Si, Ge, Sn, Ti, Zr, and Hf, and which are activated byat least one element selected from the rare earth elements. The nitridephosphor used in the present invention absorbs visible light andultraviolet light emitted from the LED chip 10100 and light emitted fromthe YAG phosphor to be excited, thus emitting light. Exemplarily nitridephosphors include Ca—Ge—N:Eu, Z; Sr—Ge—N:Eu, Z; Sr—Ca—Ge—N:Eu, Z;Ca—Ge—O—N:Eu, Z; Sr—Ge—O—N:Eu, Z; Sr—Ca—Ge—O—N:Eu, Z; Ba—Si—N:Eu, Z;Sr—Ba—Si—N:Eu, Z; Ba—Si—O—N:Eu, Z; Sr—Ba—Si—O—N:Eu, Z; Ca—Si—C—N:Eu, Z;Sr—Si—C—N:Eu, Z; Sr—Ca—Si—C—N:Eu, Z; Ca—Si—C—O—N:Eu, Z; Sr—Si—C—O—N:Eu,Z; Sr—Ca—Si—C—O—N:Eu, Z; Mg—Si—N:Eu, Z; Mg—Ca—Sr—Si—N:Eu, Z;Sr—Mg—Si—N:Eu, Z; Mg—Si—O—N:Eu, Z; Mg—Ca—Sr—Si—O—N:Eu, Z;Sr—Mg—Si—O—N:Eu, Z; Ca—Zn—Si—C—N:Eu, Z; Sr—Zn—Si—C—N:Eu, Z;Sr—Ca—Zn—Si—C—N:Eu, Z; Ca—Zn—Si—C—O—N:Eu, Z; Sr—Zn—Si—C—O—N:Eu, Z;Sr—Ca—Zn—Si—C—O—N:Eu, Z; Mg—Zn—Si—N:Eu, Z; Mg—Ca—Zn—Sr—Si—N:Eu, Z;Sr—Zn—Mg—Si—N:Eu, Z; Mg—Zn—Si—O—N:Eu, Z; Mg—Ca—Zn—Sr—Si—O—N:Eu, Z;Sr—Mg—Z n—Si—O—N:Eu, Z; Ca—Zn—Si—Sn—C—N:Eu, Z; Sr—Zn—Si—Sn—C—N:Eu, Z;Sr—Ca—Zn—Si—Sn—C—N:Eu, Z; Ca—Zn—Si—Sn—C—O—N:Eu, Z; Sr—Zn—Si—Sn—C—O—N:Eu,Z; Sr—Ca—Zn—Si—Sn—C—O—N:Eu, Z; Mg—Zn—Si—Sn—N:Eu, Z;Mg—Ca—Zn—Sr—Si—Sn—N:Eu, Z; Sr—Zn—Mg—Si—Sn—N:Eu, Z; Mg—Zn—Si—Sn—O—N:Eu,Z; Mg—Ca—Zn—Sr—Si—Sn—O—N:Eu, Z; and Sr—Mg—Zn—Si—Sn—O—N:Eu, Z. Zrepresents a rare earth element, and preferably contains at least oneselected from the group consisting of Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho,Er, and Lu. In addition, Sc, Sm, Tm, or Yb may be contained. These rareearth elements are present in an element, oxide, imide, or amide form ina mixture of materials. While most rare earth elements have trivalentelectron configurations, Yb and Sm have divalent configurations, and Ce,Pr and Tb have tetravalent configurations. If an oxide of a rare earthmetal is used, the oxygen affects the emission characteristics of thephosphor. Specifically, the presence of oxygen may undesirably degradethe luminance of emitted light, but reduces afterglow advantageously. Inuse of Mn, the grain size can be increased by the flux effect of Mn andO, and accordingly the emission luminance is enhanced. In the presentinvention, preferably, silicon nitride phosphors containing Mn are used,which include Sr—Ca—Si—N:Eu, Ca—Si—N:Eu, Sr—Si—N:Eu, Sr—Ca—Si—O—N:Eu,Ca—Si—O—N:Eu, and Sr—Si—O—N:Eu. Such phosphors are expressed by thegeneral formula L_(X)Si_(Y)N_((2/3X+4/3Y)):Eu orL_(X)Si_(Y)O_(Z)N_((2/3X+4/3Y−2/3Z)):Eu (L represents Sr, Ca, or Sr andCa). X and Y are arbitrarily selected, but preferably X=2 and Y=5 or X=1and Y=7. Specifically, preferred phosphors include(Sr_(X)Ca_(1-x))₂Si₅N₈:Eu, Sr₂Si₅N₈:Eu, Ca₂Si₅N₈:Eu,Sr_(x)Ca_(1-x)Si₇N₁₀Eu, SrSi₇N₁₀:Eu, and CaSi₇N₁₀:Eu which contain Mn.These phosphors may further contain at least one selected from the groupconsisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, and Ni. However,the present invention is not limited to the form of the presentembodiment and examples.

L represents Sr, Ca, Sr, or Ca. The Sr content and the Ca content may bevaried if necessary.

Use of Si in the phosphor composition can provide a highly crystalline,inexpensive phosphor. Europium Eu being a rare earth element is used inthe center of emission. Europium is mainly divalent or trivalent.Examples of such a phosphor composition include, but not limited to,Sr₂Si₅N₈:Eu, Pr; Ba₂Si₅N₈:Eu, Pr; Mg₂Si₅N₈:Eu, Pr; Zn₂Si₅N₈:Eu, Pr;SrSi₇N₁₀:Eu, Pr; BaSi₇N₁₀:Eu, Ce; MgSi₇N10:Eu, Ce; ZnSi₇N₁₀:Eu, Ce;Sr₂Ge₅N₈:Eu, Ce; Ba₂Ge₅N8:Eu, Pr; Mg₂Ge5N8:Eu, Pr; Zn₂Ge5N8:Eu, Pr;SrGe₇N₁₀:Eu, Ce; BaGe₇N₁₀:Eu, Pr; MgGe₇N₁₀:Eu, Pr; ZnGe₇N₁₀:Eu, Ce;Sr_(1.8)Ca_(0.2)Si₅N₈:Eu, Pr; Ba_(1.8)Ca_(0.2)Si₅N₈:Eu, Ce;Mg_(1.8)Ca_(0.2)Si₅N₈:Eu, Pr; Zn_(1.8)Ca_(0.2)Si₅N₈:Eu, Ce;Sr_(0.8)Ca_(0.2)Si₇N₁₀:Eu, La; Ba_(0.8)Ca_(0.2)Si₇N₁₀:Eu, La;Mg_(0.8)Ca_(0.2)Si₇N₁₀:Eu, Nd; Zn_(0.8)Ca_(0.2)Si₇N₁₀:Eu, Nd;Sr_(0.8)Ca_(0.2)Ge₇N₁₀:Eu, Tb; Ba_(0.8)Ca_(0.2)Ge₇N₁₀:Eu, Tb;Mg_(0.8)Ca_(0.2)Ge₇N₁₀:Eu, Pr; Zn_(0.8)Ca_(0.2)Ge₇N₁₀:Eu, Pr;Sr_(0.8)Ca_(0.2)Si₆GeN₁₀:Eu, Pr; Ba_(0.8)Ca_(0.2)SiGeN₁₀:Eu, Pr;Mg_(0.8)Ca_(0.2)Si₆GeN₁₀:Eu, Y; Zn_(0.8)Ca_(0.2)Si₆GeN₁₀:Eu, Y;Sr₂Si₅N₈:Pr; Ba₂Si₅N₈:Pr; Sr₂Si₅N₈:Tb; and BaGe₇N₁₀:Ce.

The nitride phosphor absorbs part of the blue light emitted from the LEDchip 10000 and emits light in a region from yellow to red. By using thenitride phosphor together with the YAG phosphor in the above-describedlight-emitting apparatus 20000, blue light emitted from the LED chip10000 is mixed with yellow to red light from the nitride phosphor. Thus,the light-emitting apparatus emits warm white light. In addition to thenitride phosphor, an yttrium aluminum oxide phosphor activated cerium ispreferably added. By adding the yttrium aluminum oxide phosphor, adesired color can be prepared. The yttrium aluminum oxide phosphoractivated cerium absorbs part of the blue light emitted from the LEDchip 10100 and emits light in a yellow region. Then, the blue lightemitted from the LED chip 10000 and the yellow light of the yttriumaluminum oxide phosphor are mixed to produce bluish white light. Hence,by mixing the yttrium aluminum oxide phosphor and a phosphor emittingred light into the light-transmissive coating 10500 so that lightemitted from the LED chip is combined with blue light, thelight-emitting apparatus can emit mixed white light. Particularlypreferably, white light of the light-emitting apparatus has achromaticity lying on the locus of blackbody radiation in thechromaticity diagram. In order to provide a light-emitting apparatusproducing a desired color temperature, the amount of yttrium aluminumoxide phosphor and the amount of phosphor emitting red light may beappropriately adjusted. The special color rendering index R9 of theresulting light-emitting apparatus emitting mixed white light isimproved. Known white light-emitting apparatuses including a combinationof a known blue light-emitting device and a yttrium aluminum oxidephosphor activated by cerium has a special color rendering index R9 ofabout 0 at a color temperature Tcp of about 4600 K, and hence it doesnot ensure sufficient red components. Accordingly, to increase thespecial color rendering index R9 has been a challenge. In the presentinvention, a phosphor emitting red light is used in combination with theyttrium aluminum oxide phosphor, and thus the special color renderingindex R9 can be increased to about 40 at a color temperature Tcp ofabout 4600 K.

(Light-Emitting Apparatus 20000)

FIG. 55 shows a light-emitting apparatus including the light-emittingdevice 10000 and composite 10300 mounted on the mounting base 20100according to Embodiment 11 of the present invention. In thelight-emitting apparatus 20000, a lead 21000 is fixed by an apparatusbase 22000 so that one side of the lead serves as a mount lead ormounting base 20100. The light-emitting device 10000 (device composite10400) is placed in the housing recess of the mounting base 20100, witha junction layer 11400 (adhesion layer 20400) between the device 10000and the bottom surface of the housing recess. The sidewalls of therecess (and opening 22500) may be used as a reflector 20300, and themounting base 20100 may have a function as a heat radiator and beconnected to an external radiator. The opening 22500 of the apparatusbase 20200 is formed in the light-extracting region 22300. The mountingbase 20100 may have terraces 222000 for mounting other devices, such asa shielding device, in its outer regions. The recess 20200 and theopening of the apparatus base 22000 are closed with a light-transmissivesealing member 23000. In addition, a reflector 20300 is provided outsidethe recess. The lead electrode 21000 includes an internal lead 21100 inthe base 22000 and an external lead 21200 extending to the outside ofthe base 22000, and connects to the outside. The light-emitting device10000 (device composite 10300) is electrically connected to the leads21000 with a wire 25000 and an electrical junction 20400.

Embodiment 11 is involved in the light-emitting apparatus 20000 in whichthe light-emitting device 10000 is mounted in the mounting base 21000isolated from the lead 21000, using the adhesion member 20400, as shownin FIG. 55. The housing recess 20100 of the light-emitting device 10000is provided with the reflector 20300, and may be connected to anexternal heat radiator to serves as a heat radiator 20500. Thelight-emitting device 10000 is electrically connected to the internallead 21100 with a wire 25000, and the lead 21000 is extended to theoutside to establish electrical connection. By separating the mountingbase 20100 from the lead 21000, the light-emitting apparatus comes toease of thermal design. The recess 20200, the reflector 22100 of thebase 22000 (22000 a and 22000 b), and the terrace 22200 are sealed withthe light-transmissive sealing member 23000 as shown in FIG. 56. Byproviding an optical lens to the sealing member 23000, or by forming thesealing member 23000 into a lens 24000, light emission having a desireddirectivity can be obtained.

The internal surfaces 22100 and 22200 of the recess of the package 22000may be embossed to increase the adhesion area, or subjected to plasmatreatment to enhance the adhesion to the molding member 23000. Thesidewall of the recess of the package 22000 is preferably diverged inthe open side tapered (tapered). Since such a shape allows light emittedfrom the light-emitting device to reflect from the sidewall of therecess to the front side of the package, the light-extraction efficiencycan be increased. The package 22000 may be integrally formed togetherwith the external electrode 21200, or a plurality of portions of thepackage 22000 may be assembled. The package 22000 is easily formed by,for example, insert molding. Exemplary materials of the package includeresins, such as polycarbonate resin, polyphenylene sulfide (PPS), liquidcrystal polymer (LCP), ABS resin, epoxy resin, phenol resin, acrylicresin, and PBT resin, ceramics, and metals. In use at high power of alight-emitting apparatus emitting light including ultraviolet light, itis expected that the ultraviolet light degrades the resin to discolorthe resin color into yellow. Thus, the emission efficiency is reduced,and the mechanical strength of the resin is degraded to shorten thelifetime. It is therefore preferable that the package is made of ametal. A metal package is not degraded in contrast to the resin packageeven if the LED chip emitting light including ultraviolet light is usedat high power.

Various types of colorant may be used to color the package 22000 dark.For example, Cr₂O₈, MnO, Fe₂O₃, and carbon black are suitable.

A thermosetting resin may be used for bonding the LED chip 10000 and thepackage 22000. Examples of such a resin include epoxy resin, acrylicresin, and imide resin. The external electrode 21200 is preferablyformed by plating the surface of a copper or phosphor bronze plate witha metal, such as palladium or gold, or a solder. If the externalelectrode 21200 is disposed on an apparatus base 22000 made of glassepoxy resin or ceramic, a copper foil or a tungsten film may be used asthe external electrode 21200.

The conductive wire 25000 has a diameter in the range of 10 to 70 μm.Examples of the conductive wire 25000 include gold, copper, platinum,and aluminum wires and their alloy wires. The conductive wire 25000 caneasily establish connection between the electrode of the LED chip 10000and the internal lead and mount lead, using a wire bonding apparatus.

In order to protect the LED chip 10000, the conductive wire 25000, andthe coating 22100 or 10500 containing the phosphor, according to theapplications of the light emitting apparatus, or in order to enhance thelight-extraction efficiency, the molding member 23000 may be provided.The molding member 23000 is formed of a resin or glass. Preferredmaterials of the molding member 23000 include transparentweather-resistant resins and glass, such as epoxy resin, urea resin,silicone resin, and fluorocarbon resin. By mixing a diffusing agent intothe molding member, the directivity of the LED chip 10000 can be reducedto increase the viewing angle. The molding member 23000 may be made ofthe same material as the binder of the coating layer or a differentmaterial.

If the LED chip 10000 is airtightly sealed together with nitrogen gas ina metal package, the molding member 23000 is not necessary. If an LEDchip emitting ultraviolet light is used in the light-emitting device, anultraviolet-resistant resin, such as fluorocarbon resin, may be used forthe molding member.

For another form of the light-emitting apparatus 20000, a metal base22000 is combined with a mounting base 20100 (recess 20200) or a mountlead provided on one side of the lead, and the light-emitting device10000 (device composite 10300) is mounted in the mounting base or mountlead. The base 22000 is provided with an isolated lead 21000, and isairtightly sealed with a sealant or cap (made of, for example, a metal)having a window, with an inert gas, such as nitrogen, oxygen, or theirmixture, filling the base. The light-emitting device 10000 may bedirectly placed in at least one recess 20200 in a metal substrate, andan optical member, such as a lens, may be provided over thecorresponding recess.

A plurality of the light-emitting devices 10000 (device composites10300) may be integrally mounted in a single housing 20200 (mountingbase 20100), or a plurality of mounting bases (or a plurality housing20200 in the base 2010), each having the light-emitting device 10000(composite 10300) are provided in a single apparatus base 22000. Variousmodifications may be made according to required characteristics.

INDUSTRIAL APPLICABILITY

The semiconductor light-emitting device according to the presentinvention allows active and efficient light extraction in a desireddirection. The light-emitting device exhibits high light-extractionefficiency and high power. The light-emitting apparatus including thelight-emitting device also exhibits superior characteristics in, forexample, power.

1. A nitride semiconductor light-emitting device comprising: a pluralityof structured portions, each of the structured portions including ann-type semiconductor layer provided on a lower side, and a p-typesemiconductor layer provided on an upper side, an active layer betweenthe n-type semiconductor layer and the p-type semiconductor layer, andan n-electrode; and wherein each of the structured portions has at leastan inclined side surface at which a side surface of the n-typesemiconductor layer is exposed and a lower surface with a larger widththan a width of the upper side thereof in sectional view, and then-electrode has a plurality of contact portions disposed on the sidesurface of the n-type semiconductor layer in each of the structuredportions.
 2. The nitride semiconductor light-emitting device accordingto claim 1, wherein the n-electrode surrounds each of the structuredportions.
 3. The nitride semiconductor light-emitting device accordingto claim 1, further comprising a substrate, and the plurality of thestructured portions being disposed on the substrate; wherein then-electrode continuously extends to the lower surface of the substratethrough the side surfaces of the substrate.
 4. The nitride semiconductorlight-emitting device according to claim 1, wherein each of thestructured portions has at least one of a circular shape and arectangular shape.
 5. The nitride semiconductor light-emitting deviceaccording to claim 1, wherein each of the structured portions has atleast one of a hexagonal shape and a polygonal shape.
 6. The nitridesemiconductor light-emitting device according to claim 1, wherein thestructured portions are respectively spaced away from each other, andthe n-electrode has an interconnect portion extended from the contactportions, and the contact portions are connected to each other with theinterconnect portion therebetween.
 7. The nitride semiconductorlight-emitting device according to claim 6, wherein the structuredportions have respective p-electrodes in ohmic contact with therespective p-type semiconductor layers, and the p-electrodes areconnected to each other.
 8. The nitride semiconductor light-emittingdevice according to claim 1, further comprising a reflection layercovering the structured portions.
 9. The nitride semiconductorlight-emitting device according to claim 8, wherein the reflection layeris a metal layer covering the structured portions with an insulatinglayer therebetween.
 10. The nitride semiconductor light-emitting deviceaccording to claim 9, wherein the metal layer serves as a connectingelectrode for connecting p-electrodes of p-type semiconductor layers ofthe structured portions.
 11. The nitride semiconductor light-emittingdevice according to claim 8, wherein the reflection layer comprises adielectric multilayer film.
 12. The nitride semiconductor light-emittingdevice according to claim 1, wherein the inclined side surface has aconvex surface protuberating outward.
 13. A nitride semiconductorlight-emitting device comprising: a plurality of structured portions,each of the structured portions including an n-type semiconductor layerprovided on a lower side, and a p-type semiconductor layer provided onan upper side, an active layer between the n-type semiconductor layerand the p-type semiconductor layer, and an n-electrode; and wherein eachof the structured portions has at least an inclined side surface with aside surface of the n-type semiconductor layer forming a portion of theinclined side surface of each of the structured portions and a lowersurface with a larger width than a width of the upper side thereof insectional view, and the n-electrode has a plurality of contact portionsdisposed on the side surface of the n-type semiconductor layer in eachof the structured portions.
 14. The nitride semiconductor light-emittingdevice according to claim 13, wherein a portion of the n-electrodesurrounds a portion of the side surface of the n-type semiconductorlayer of each of the structured portions.
 15. The nitride semiconductorlight-emitting device according to claim 13, further comprising asubstrate, and the plurality of the structured portions being disposedon the substrate; wherein the n-electrode continuously extends to thelower surface of the substrate by extending along the side surfaces ofthe substrate.
 16. The nitride semiconductor light-emitting deviceaccording to claim 13, wherein each of the structured portions has theupper side that is at least one of a circular shape and a rectangularshape.
 17. The nitride semiconductor light-emitting device according toclaim 13, wherein each of the structured portions has the upper sidethat is at least one of a hexagonal shape and a polygonal shape.